Methods of producing metallocene catalyst components

Abstract

The present disclosure relates to a method of producing a metallocene complex. The method comprises reacting a C1-symmetric, bridged bisindenyl metallocene in its syn-configuration with an organometallic reagent selected from an organolithium of the formula R"Li and a Grignard reagent of the formula RMg-X', wherein R and R" are each independently C1 to C6 alkyl or benzyl, and X' is halogen. The C1-symmetric, bridged bisindenyl metallocene in its syn-configuration is epimerised into its corresponding anti-configuration.

Description

[0001] METHODS OF PRODUCING METALLOCENE CATALYST COMPONENTS FIELD OF THE DISCLOSURE The present disclosure relates to a method of producing a metallocene complex. The method comprises reacting a C1-symmetric, bridged bisindenyl metallocene in its syn- configuration with an organometallic reagent in order to epimerise the syn-C1-symmetric, bridged bisindenyl metallocene into its anti-configuration. BACKGROUND OF THE DISCLOSURE Metallocene catalysts have been used to manufacture polyolefins for many years. Many academic and patent publications describe the use of these catalysts in olefin polymerization. Metallocenes are now used industrially and polyethylenes and polypropylenes in particular are often produced using cyclopentadienyl-based catalyst systems with different substitution patterns. Generally, metallocene complexes designed for the production of isotactic polyolefins are racemic bisindenyl metallocene complexes in the anti-configuration. Typically, however, such metallocene complexes are synthesised as a mixture of the anti- and syn- isomers. Formation of the syn- isomer is detrimental as it consumes expensive organic ligand precursor and in addition can lead to the production of lower molecular weight, amorphous polymers. The process of removing the syn isomer from the metallocene isomer mixture requires additional preparation steps and can also lead to partial losses of the desired anti isomer, decreasing the overall efficiency of the synthesis process. Various approaches have been taken to selectively produce the anti-isomer. The first involves the modification of the transition metal salt used in the metalation step. Examples of this approach are described in WO1999 / 015538, WO2004037840 and US7098354, LoCoco et al, “Chelate-Controlled Synthesis of Racemic ansa-Zirconocenes“, Journal of the American Chemical Society 2004, 126, 15231 and WO2005 / 108408. Although this approach can improve the final yield of the desired metallocene isomer, the procedures described in these references add several steps to the overall synthesis protocol. A second approach is the decomposition of the unwanted isomer, usually by the addition of an alcohol or other protic reagent. In some cases, this approach can facilitate improved

[0002] Sensitivity: Internal isolation of the desired isomer. However, the approach is generally not sufficiently selective, and can lead to the decomposition of some of the desired isomer, resulting in undesirable decreases in the overall yield of the desired isomer. This approach is described for example in EP 819695. A third approach requires the use of a racemic ligand having two Si or Sn leaving groups, as described for example in Nifant'ev et al, “Synthesis of Zirconium and Hafnium ansa- Metallocenes via Transmetalation of Dielement-Substituted Bis(cyclopentadienyl) and Bis(indenyl) Ligands”, Organometallics 1997, 16(4), 713-715 and in Resconi et al, “Diastereoselective Synthesis, Molecular Structure, and Solution Dynamics of meso- and rac-[Ethylenebis(4,7-dimethyl-η5-1-indenyl)]zirconium Dichloride Isomers and Chain Transfer Reactions in Propene Polymerization with the rac Isomer“, Organometallics, 1996, 15, 5046-5059. However, this approach has drawbacks: silicon bridged ligands involve SnMe3as leaving groups, involving the use of toxic tin compounds. Furthermore, more than 50% of the starting bridged ligand needs to be discarded, compromising the economic viability and sustainability of the process. A fourth approach requires a chemical modification of the ligand structure of the metallocene catalyst to make the structure more stereo-directing towards the desired isomer by means of tuned steric hindrance. For example, the synthesis of a 4,8-diphenyl-indacene and corresponding C1-symmetric complex (with one 2-iPr substituent) and polymerisation performance are described in WO 2005 / 058916 and Nifant’ev et al, “Asymmetric ansa- Zirconocenes Containing a 2-Methyl-4-aryltetrahydroindacene Fragment: Synthesis, Structure, and Catalytic Activity in Propylene Polymerization and Copolymerization”, Organometallics 2011, 30(21), 5744-5752,. In both these references, the complex was obtained in low yield and with low diastereoselectivity. Furthermore, decomposition of both anti and syn isomers was observed. Similarly, in EP3768735, a bisindenyl ligand carrying an additional aryl group in the back (position 8) of an indacenyl ligand has been shown to increase the anti / syn ratio of the complex up to 90:10. A fifth approach involves epimerisation. Epimerisation is a reaction that inverts the chirality of an asymmetric atom or molecule. In the case of metallocenes, this reaction can be used to interconvert rac- and meso- or syn- and anti- metallocene isomers by means of a catalyst such as LiCl or MgCl2in THF. In a few cases, this reaction proved efficient in enriching the isomer mixture in the desired isomer (rac or anti), but it is often accompanied by decomposition, especially when high reaction temperature is required to increase the reaction rate. This

[0003] Sensitivity: Internal method has been shown to increase the yield of the desired isomer provided this is the least soluble organometallic compound in the mixture, but may also be accompanied by decomposition. Examples can be found, for example, in WO 98 / 020014. Also certain ammonium halides have been shown to act as epimerisation catalysts, as described in WO2005 / 030783. BRIEF DESCRIPTION OF THE DISCLOSURE An object of the present disclosure is to provide a new method of converting a metallocene complex from its syn- form to its anti-form. The method comprises reacting a C1-symmetric, bridged bisindenyl metallocene in its syn-configuration with an organometallic reagent selected from an organolithium of the formula R” Li and a Grignard reagent of the formula RMg-X’, wherein R and R” are each independently C1to C6alkyl or benzyl, and X’ is halogen. Preferably, the starting C1-symmetric, bridged bisindenyl metallocene comprises a mixture of syn- and anti-isomers. Following reaction with the organometallic reagent, the proportion of the anti-isomer may be increased. BRIEF DESCRIPTION OF THE DRAWINGS In the following the disclosure will be described in greater detail by means of preferred embodiments with reference to the accompanying drawings, in which: Figure 1 shows a comparison of the rates of epimerization observed with the metallocene catalyst components, MC1 and Comp. MC5 in Example 14. DEFINITIONS Throughout the description, the following definitions are employed: The term “C1-C20-hydrocarbyl” includes C1-C20-alkyl, C2-C20-alkenyl, C2-C20-alkynyl, C3-C20- cycloalkyl, C3-C20-cycloalkenyl, C6-C20-aryl, C7-C20-alkylaryl, and C7-C20-arylalkyl groups or of course mixtures of these groups such as cycloalkyl substituted by alkyl. Unless otherwise stated, preferred C1-C20-hydrocarbyl groups are C1-C20-alkyl, C4-C20-cycloalkyl, C5-C20- cycloalkyl-alkyl groups, C7-C20-alkylaryl groups, C7-C20-arylalkyl groups, and C6-C20-aryl groups, especially C1-C10-alkyl groups, C6-C10-aryl groups, and C7-C12-arylalkyl groups, e.g. C1-C8 alkyl groups. Most especially preferred hydrocarbyl groups are methyl, ethyl, propyl, isopropyl, n-propyl, tert-butyl, isobutyl, C5-C6-cycloalkyl, cyclohexylmethyl, phenyl, and benzyl.

[0004] Sensitivity: Internal The term “C1-C10-hydrocarbyl” includes C1-C10-alkyl, C2-C10-alkenyl, C2-C10-alkynyl, C3-C10-cycloalkyl, C3-C10-cycloalkenyl, C6-C10-aryl, C7-C10-alkylaryl, and C7-C10-arylalkyl groups or of course mixtures of these groups such as cycloalkyl substituted by alkyl. Unless otherwise stated, preferred C1-C10-hydrocarbyl groups are C1-C10-alkyl, C4-C10-cycloalkyl, C5-C10-cycloalkyl-alkyl groups, C7-C10-alkylaryl groups, C7-C10-arylalkyl groups, and C6-C10-aryl groups, especially C1-C6-alkyl groups, C6-aryl groups, and C7-C10-arylalkyl groups, e.g. C1- C6-alkyl groups. Most especially preferred hydrocarbyl groups are methyl, ethyl, propyl, isopropyl, n-propyl, tert-butyl, isobutyl, C5-C6-cycloalkyl, cyclohexylmethyl, phenyl, and benzyl. It is to be noted that linear and branched hydrocarbyl groups cannot contain cyclic units. Aliphatic hydrocarbyl groups cannot contain aryl rings. The term “heteroatoms of Group 14-16 of the Periodic Table” includes for example Si, N, O, P or S. The term “C 1 4-C8-ring” as used herein in connection to -R 2Si-, refers to cyclic groups containing 4 to 8 carbon atoms and a Si atom and includes for example silacycloalkanediyls, such as silacyclobutane, silacyclopentane, or 9-silafluorene. The term “halogen” includes fluoro, chloro, bromo, and iodo groups, especially chloro or fluoro groups. The term “aryl” is used to denote groups derived from arenes by removal of a hydrogen atom from a ring carbon atom. Suitable aryls include 6 to 22 carbon atoms in the aryl ring, preferably 6 to 10 carbon atoms in the aryl ring. Suitable aryl groups include phenyl, naphthyl or a mono-, di-, tri or tetra-hydronapthalenyl group. The term “heteroaryl” refers to groups derived from heteroarenes. Suitable heteroaryls include C3-C20 heteroaryl containing up to two heteroatoms (O, S, N, P). Each aryl or heteroaryl group may be substituted by one or more substituents selected from halogen (e.g. F, Cl, Br, I) and C1 - C20 hydrocarbyl. The C1 - C20 hydrocarbyl may optionally contain up to two heteroatoms from Group 14-16 of the Periodic Table (e.g. O, S, N, P). Examples of suitable substituents for Ar may be aryl (e.g. phenyl) or alkyl, such as C1 to C10 alkyl, for example, methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, n-pentyl, i-pentyl and hexyl. Other examples of suitable substituents include alkoxy groups, for example, a methoxy, ethoxy, propoxy or butoxy. Alternatively or additionally, each aryl or heteroaryl group may be substituted with two adjacent groups that can form part of a cyclic structure of 4 to 7 atoms, for example a cyclic structure of 5 or 6 carbons, including the carbon atoms of the aryl or heteroaryl ring to which they are bound.

[0005] Sensitivity: Internal Examples of suitable Ar groups include 4-methylphenyl, 3-methylphenyl, 2-methylphenyl, 4- ethylphenyl, 3-ethylphenyl, 2-ethylphenyl, 4-phenylphenyl, 3-phenylphenyl, 2-phenylphenyl, 4-tert-butylphenyl, 3-tert-butylphenyl, 4-methoxyphenyl, 3,5-dimethylphenyl, 3,5- diisopropylphenyl, 3,5-ditertbutylphenyl, 3,5-ditertbutyl-4-methoxyphenyl, 1-naphthyl, 2- naphthyl, 5,6,7,8-tetrahydronaphthalen-1-yl, 5,6,7,8-tetrahydronaphthalen-2-yl, 9-fluorenyl. The oxidation state of the metal ion is governed primarily by the nature of the metal ion in question and the stability of the individual oxidation states of each metal ion. It is appreciated that in the complexes of the invention, the metal ion is coordinated by ligands X to satisfy the valence of the metal ion and to fill its available coordination sites. The numbering of these rings will be evident from the structures indicated herein. The term “consisting essentially of” is used herein to refer to that further components may be present namely those not materially affecting the essential characteristics of the compound or composition e.g. minor amounts of impurities. DETAILED DESCRIPTION OF THE DISCLOSURE The metallocene complexes employed in the present disclosure are asymmetrical. Asymmetrical means simply that the two cyclopentadienyl ligands bound to the metallocene are different, that is, each ligand bears a set of substituents that are chemically different. Although the complexes employed in the present invention are formally C1-symmetric, the complexes ideally retain a pseudo-C2-symmetry since they maintain C2-symmetry in close proximity of the metal center although not at the ligand periphery. By nature of their chemistry both anti and syn enantiomer pairs (in case of C1-symmetric complexes) are generally formed during the synthesis of metallocene complexes. For the purpose of this invention, racemic-anti means that the two indenyl ligands are oriented in opposite directions with respect to the cyclopentadienyl-metal-cyclopentadienyl plane, while racemic-syn means that the two indenyl ligands are oriented in the same direction with respect to the cyclopentadienyl-metal-cyclopentadienyl plane, as shown in the scheme below. In the context of this disclosure, a reference to syn is a reference to racemic-syn and a reference to anti is a reference to racemic-anti.

[0006] Sensitivity: Internal Racemic Anti Racemic Syn Viewed from a first aspect, the present invention provides a method of producing a metallocene complex. The method comprises reacting a C1-symmetric, bridged bisindenyl metallocene in its syn-configuration with an organometallic reagent selected from an organolithium of the formula R”Li and a Grignard reagent of the formula RMg-X’, wherein R” and R are independently selected from C1 to C6 alkyl or benzyl, and X’ is halogen. The C1- symmetric, bridged bisindenyl metallocene in its syn-configuration has the Formula (1): wherein: Mt is Zr or Hf; X is halogen or an -OY group or an -NY2 group, wherein Y is a C1 to C20 hydrocarbyl group, optionally containing up to two heteroatoms from Group 14-16 of the Periodic Table; each Ar is independently selected from aryl and heteroaryl containing up to two heteroatoms from Group 15-16 of the Periodic Table; each aryl and / or heteroaryl being optionally substituted with a substituent selected from halogen and C1- C20hydrocarbyl,

[0007] Sensitivity: Internal said C1- C20hydrocarbyl optionally containing up to two heteroatoms from Group 14-16 of the Periodic Table; each R1is independently selected from H; C1to C20hydrocarbyl, optionally containing up to two heteroatoms from Group 14-16 of the Periodic Table; or, together with the Si atom to which the R1atoms are attached, form a C4to C8ring; R2and R2’are, independently from each other, C1to C20hydrocarbyl, optionally containing up to two heteroatoms from Group 14-16 of the Periodic Table; R5and R6are, independently from each other, H or C1to C20hydrocarbyl, optionally containing up to two heteroatoms from Group 14-16 of the Periodic Table; or, together with the C atoms to which they are attached, R5and R6form a C4to C7ring; R5’is H or C1to C20hydrocarbyl group, optionally containing up to two heteroatoms from Group 14-16 of the Periodic Table; or a -OY group; and R6’is a tertiary hydrocarbyl of the formula -CRx3, with Rxbeing a linear or branched C1to C6alkyl group, C3to C8cycloalkyl group or C6to C10aryl group. Preferably, the C1-symmetric, bridged bisindenyl metallocene in its syn-configuration is of the Formula (2) wherein: Mt is Zr or Hf; X is halogen, an -OY group or an -NY2group, wherein Y is a C1to C20hydrocarbyl group, optionally containing up to two heteroatoms from Group 14-16 of the Periodic Table; each R1is independently selected from H; C1to C20hydrocarbyl, optionally containing up to two heteroatoms from Group 14-16 of the Periodic Table; or, together with the Si atom to which the R1atoms are attached, form a C4to C8ring;

[0008] Sensitivity: Internal R2and R2’are, independently from each other, of the formula -CHRy2or -CH2Ry, with Rybeing H, a linear or branched C1to C6alkyl group, C3to C8cycloalkyl group or C6to C10aryl group; R3and R4are, independently from each other, H; C1to C20hydrocarbyl, optionally containing up to two heteroatoms from Group 14-16 of the Periodic Table or wherein two adjacent R3or R4groups, together with the carbon atoms of the phenyl to which they are bound, form part of a C4to C7ring; R5and R6are, independently from each other, H or C1to C20hydrocarbyl, optionally containing up to two heteroatoms from Group 14-16 of the Periodic Table; or, together with the C atoms to which they are attached, R5and R6form a C4to C7ring; R5’is H or C1to C20hydrocarbyl group, optionally containing up to two heteroatoms from Group 14-16 of the Periodic Table; or a -OY group; and R6’is a tertiary hydrocarbyl of the formula -CRx3, with Rxbeing a linear or branched C1to C6alkyl group, C3to C8cycloalkyl group or C6to C10aryl group. Preferably, R6’is of the formula -C(CH3)3 and / or, preferably, R5’ is OY, where Y is a C1 to C6 hydrocarbyl, optionally containing up to two silicon atoms. Y is most preferably methyl. Where X is halogen, X is preferably Cl. Preferably, the C1-symmetric, bridged bisindenyl metallocene in its syn-configuration is reacted with a Grignard reagent of the formula RMg-X’, wherein R is C1 to C6 alkyl or benzyl, and X’ is halogen. More preferably, X’ is Cl. Preferably R is C1 to C5, C1 to C4 or C1 to C3 alkyl, more preferably R is methyl, ethyl or benzyl, even more preferably methyl. In some embodiments, the C1-symmetric, bridged bisindenyl metallocene in its syn- configuration is reacted with an organolithium of the formula R”Li, wherein R” is C1 to C5, C1 to C4 or C1 to C3 alkyl, more preferably R is methyl, ethyl or benzyl, even more preferably methyl is methyl. Preferably, a mixture of the syn- and anti- isomers of the C1-symmetric, bridged bisindenyl metallocene is reacted with the organometallic reagent. As discussed above, the syn-isomer of the C1-symmetric, bridged bisindenyl metallocene has the Formula (1) above. The anti- isomer of the C1-symmetric, bridged bisindenyl metallocene has the Formula (1’) below, with R1, R2, R2’, R5, R5’, R6, R6’, Ar, Mt and X as defined above in relation to Formula (1) above:

[0009] Sensitivity: Internal Where the syn-isomer of the C1-symmetric, bridged bisindenyl metallocene has the Formula (2) above, the syn-isomer may be reacted with the organometallic reagent as a mixture that also includes the anti-isomer. For the avoidance of doubt, the anti-isomer of the compound of Formula (2) has the Formula (2’) below, where R1, R2, R2’, R3, R4, R5, R5’, R6, R6’, Mt and X are as defined in relation to Formula (2) above: Where a mixture of syn- and anti- isomers of the C1-symmetric, bridged bisindenyl metallocene is reacted with the organometallic reagent, the mixture may have an anti / syn ratio of ≥ 1:99, for example, ≥ 10:90, ≥ 20:80, ≥ 30:70, ≥ 40:60 or ≥ 50:50. The mixture may have an anti / syn ratio of ≥ 55:45, preferably ≥ 60:40, more preferably ≥ 65:35, even more preferably, ≥ 70:30, for example, ≥ 75:25 or ≥ 80:20. Where a mixture of syn- and anti- isomers of the C1-symmetric, bridged bisindenyl metallocene is reacted with the organometallic reagent the mixture may have an anti / syn ratio of ≤ 90:10, preferably ≤ 88:12. Where a mixture of syn- and anti- isomers of the C1-symmetric, bridged bisindenyl metallocene is reacted with the organometallic reagent, the mixture may have an anti / syn

[0010] Sensitivity: Internal ratio of 1:99 to 95:5, for example, 10:90 to 95:5, 20:80 to 95:5, 30:70 to 95:5, 40:60 to 95:5 or 50:50 to 95:5. The mixture may have an anti / syn ratio of 55:45 to 90:10, preferably 60:40 to 90:10, more preferably 65:35 to 88:12, even more preferably, 70:30 to 88:12, for example, 75:25 or 80:20 to 88:12. Where a mixture of syn- and anti- isomers of the C1-symmetric, bridged bisindenyl metallocene is reacted with the organometallic reagent, the reaction produces a mixture of syn- and anti- isomers of a C1-symmetric, bridged bisindenyl di(C1-6alkyl) metallocene or a C1-symmetric, bridged bisindenyl di(benzyl) metallocene. Preferably, the latter mixture has an anti / syn ratio that is greater than the anti-syn ratio of the mixture of syn- and anti- isomers of the C1-symmetric, bridged bisindenyl metallocene that is reacted with the organometallic reagent. More preferably, the ratio is at least 5% greater, even more preferably 10% greater than the anti / syn ratio of the starting mixture of syn- and anti- isomers of the C1-symmetric, bridged bisindenyl metallocene that is reacted with the organometallic reagent. When the C1-symmetric, bridged bisindenyl metallocene is reacted with the organometallic reagent, the reaction may result in a mixture of syn- and anti- isomers of a C1-symmetric, bridged bisindenyl di-(C1-6alkyl) metallocene or C1-symmetric, bridged bisindenyl di(benzyl) metallocene. The latter mixture may have an anti-syn ratio that is ≥ 90:10, preferably ≥ 92:8, more preferably ≥ 95:5; even more preferably ≥ 97:3. The organometallic reagent may be reacted with the C1-symmetric, bridged bisindenyl metallocene in at least a stoichiometric amount. Preferably, the organometallic reagent is reacted with the C1-symmetric, bridged bisindenyl metallocene in a greater than stoichiometric amount. The molar ratio organometallic reagent to metallocene is at least 2:1, or between 2:1 to 1:4, preferably 2:1 to 3:1. Where the reaction produces a bridged (i.e. C1 symmetric bridged) bisindenyl di(C1-6 alkyl) metallocene or a bridged (i.e. C1 symmetric bridged) bisindenyl di(benzyl) metallocene, the method may further comprise recovering the bridged bisindenyl di(C1-6 alkyl) metallocene or bridged bisindenyl di(benzyl) metallocene in the anti- configuration by solvent extraction. Solvent extraction may be carried out in pentane, hexane and / or toluene. Where the reaction produces a bridged bisindenyl di(C1-6alkyl) metallocene or a bridged bisindenyl di(benzyl) metallocene, the method may further comprise recovering the bridged bisindenyl di(C1-6 alkyl) metallocene or bridged bisindenyl di(benzyl) metallocene produced, and polymerising propylene and optionally at least one comonomer selected from ethylene and C4 to C10 alpha olefin comonomers with a catalyst comprising the recovered bridged Sensitivity: Internal bisindenyl di-(C1-6alkyl) metallocene or bridged bisindenyl di-(benzyl) metallocene. The polymerisation may be carried out in the presence of a co-catalyst comprising a Group 13 element and optionally a support. Starting C1-symmetric, bridged bisindenyl metallocene of the Formula (1) As discussed above, the starting C1-symmetric, bridged bisindenyl metallocene that is reacted with the organometallic reagent has the Formula (1) For the above-defined metallocene complexes of Formula (1), the following represent preferable embodiments, which can be selected alone or in combination: In a complex of Formula (I), Mt is Zr or Hf, preferably Zr. Each X is halogen or an -OY group or an -NY2group, wherein Y is a C1to C20hydrocarbyl group, optionally containing up to two heteroatoms from Group 14-16 of the Periodic Table. Preferably, X is halogen. Suitable halogens are F, Cl and Br, preferably Cl. Each Ar is independently selected from aryl and heteroaryl containing up to two heteroatoms from Group 15-16 of the Periodic Table. Each aryl and / or heteroaryl may be optionally substituted with a substituent selected from halogen and C1- C20hydrocarbyl, said C1- C20hydrocarbyl optionally containing up to two heteroatoms from Group 14-16 of the Periodic Table. Suitable aryls include C6-C22aryls, preferably C6– C10aryls. Preferably, Ar comprises a phenyl, naphthyl or a mono-, di-, tri or tetra-hydronaphthalenyl group. Suitable heteroaryls Sensitivity: Internal include C3-C20heteroaryl containing up to two heteroatoms (O, S, N, P). Each aryl or heteroaryl group may be substituted by one or more substituents. Suitable substituents include halogen (e.g. F, Cl, Br, I), or linear or branched C1- C20hydrocarbyl groups, optionally containing up to two silicon atoms or heteroatoms (O, S, N, P). Examples of suitable substituents for Ar may be aryl (e.g. phenyl), or alkyl, such as C1to C10alkyl, for example, methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, n-pentyl, i-pentyl and hexyl. The aryl or heteroaryl may be substituted with an alkoxy group, for instance, methoxy, ethoxy, propoxy or butoxy groups. Alternatively or additionally, each aryl or heteroaryl group may be substituted with two adjacent groups that can form part of a cyclic structure of 4 to 7 atoms, for example a cyclic structure of 5 or 6 carbons, including the carbon atoms of the aryl or heteroaryl ring to which they are bound. Examples of suitable aryl groups include 4- methylphenyl, 3-methylphenyl, 2-methylphenyl, 4-ethylphenyl, 3-ethylphenyl, 2-ethylphenyl, 4-phenylphenyl, 3-phenylphenyl, 2-phenylphenyl, 4-tert-butylphenyl, 3-tert-butylphenyl, 4- methoxyphenyl, 3,5-dimethylphenyl, 3,5-diisopropylphenyl, 3,5-ditertbutylphenyl, 3,5- ditertbutyl-4-methoxyphenyl, 1-naphthyl, 2-naphthyl, 5,6,7,8-tetrahydronaphthalen-1-yl, 5,6,7,8-tetrahydronaphthalen-2-yl, 9-fluorenyl. Each R1is independently selected from H; C1 to C20 hydrocarbyl, optionally containing up to two heteroatoms from Group 14-16 of the Periodic Table; or, together with the Si atom to which the R1atoms are attached, form a C4 to C8 ring. Preferably R1are each independently, same or different from each other, C1-C10-hydrocarbyl, more preferably C1- C10-alkyl, C4-C10-cycloalkyl, C5-C10-cycloalkyl-alkyl, C7-C10-arylalkyl, C6-C10-aryl, or C7-C10- alkylaryl, such as methyl, ethyl, propyl, isopropyl, tert-butyl, isobutyl, C3-C8-cycloalkyl, cyclohexylmethyl, phenyl, or benzyl, even more preferably both are C1-C6-alkyl, C5-C6- cycloalkyl, or C6-aryl. In an embodiment each R1is independently, same or different from each other, C1-C10-alkyl or C1-C6-alkyl, optionally substituted with C1-C10-alkoxy. It is preferred that both R1groups are the same. Most preferably, both R1are methyl. In one embodiment, one R1may be selected from hydrogen, methyl, ethyl, n-propyl, i-propyl, cyclopropyl, n-butyl, i-butyl, sec-butyl, n-pentyl, i-pentyl, cyclopentyl, hexyl, octyl, and the second R1may be selected from methyl, ethyl, n-propyl, i-propyl, cyclopropyl, n-butyl, i-butyl, sec-butyl, n-pentyl, i-pentyl, cyclopentyl, n-hexyl, cyclohexyl, trimethylsilyl, phenyl, o-, m-, p- tolyl, xylyl, biphenyl, p-trimethylsilylphenyl, p-triethylsilyl. R2and R2’are, independently from each other, C1to C20hydrocarbyl, optionally containing up to two heteroatoms from Group 14-16 of the Periodic Table. The C1to C20hydrocarbyl may be a C1to C10hydrocarbyl. The hydrocarbyl may optionally contain O, S, N, P or Si, or Sensitivity: Internal OSiR3. Preferably, R2and R2’are, independently from each other, of the formula -CHRy2or - CH2Ry, with Rybeing H, a linear or branched C1to C6alkyl group, C3to C8cycloalkyl group or C6to C10aryl group. Preferably, R2and R2’are each independently a C1to C6alkyl, for example, methyl, ethyl, n-propyl and i-propyl. R5and R6are, independently from each other, H or C1to C20hydrocarbyl, optionally containing up to two heteroatoms from Group 14-16 of the Periodic Table; or, together with the C atoms to which they are attached, R5and R6form a C4to C7ring, preferably a C5ring. R5and R6may be both H. Alternatively, together with the C atoms to which they are attached, R5and R6may form a C5ring. R5’is H or C1to C20hydrocarbyl group, optionally containing up to two heteroatoms from Group 14-16 of the Periodic Table; or a -OY group. Preferably, R5’is -OY. Y is a C1to C20hydrocarbyl group, optionally containing up to two heteroatoms from Group 14-16 of the Periodic Table. Y may be C1-C10-hydrocarbyl, for example, linear or branched C1-C10- hydrocarbyl. Preferably Y is linear or branched C1-C6-alkyl, such as methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, or tert-butyl, C7-C10-arylalkyl, C7-C10-alkylaryl, or C6-C10- aryl, more preferably linear C1-C6-alkyl, branched C3-C6–alkyl, or C6-aryl, even more preferably linear C1-C4-alkyl, yet even more preferably methyl or ethyl, and most preferably methyl. R6’is a tertiary hydrocarbyl of the formula -CRx3, with Rxbeing a linear or branched C1 to C6 alkyl group, C3 to C8 cycloalkyl group or C6 to C10 aryl group. Preferably Rx’being linear C1- C3-alkyl; more preferably methyl. Thus advantageously, R6’ is tert-butyl. The C1-symmetric, bridged bisindenyl metallocene of the Formula (1) may meet the requirements of Formula (2) below. Sensitivity: Internal Mt, X, R1, R2, R2’, R5, R6, R5’and R6’may be defined as discussed in relation to Formula (1) above. Furthermore, the following are more preferred: Mt is Zr or Hf, and is preferably Zr. Each X is preferably halogen, suitably F, Cl and Br, more preferably Cl. Each R1is independently selected from H; C1to C20hydrocarbyl, optionally containing up to two heteroatoms from Group 14-16 of the Periodic Table; or, together with the Si atom to which the R1atoms are attached, form a C4to C8ring. Preferably R1are each independently, same or different from each other, C1-C10-hydrocarbyl, more preferably C1- C10-alkyl, C4-C10-cycloalkyl, C5-C10-cycloalkyl-alkyl, C7-C10-arylalkyl, C6-C10-aryl, or C7-C10-alkylaryl, such as methyl, ethyl, propyl, isopropyl, tert-butyl, isobutyl, C3-C8-cycloalkyl, cyclohexylmethyl, phenyl, or benzyl, even more preferably both are C1-C6-alkyl, C5-C6-cycloalkyl, or C6-aryl. In an embodiment each R1is independently, same or different from each other, C1-C10-alkyl or C1-C6-alkyl, optionally substituted with C1-C10-alkoxy. It is preferred that both R1groups are the same. Most preferably, both R1are methyl. R2and R2’are preferably, independently from each other, of the formula -CHRy2 or -CH2Ry, with Rybeing H, a linear or branched C1 to C6 alkyl group, C3 to C8 cycloalkyl group or C6 to C10 aryl group. Preferably, R2and R2’are each independently a C1 to C6 alkyl, for example, methyl, ethyl, n-propyl and i-propyl. Sensitivity: Internal R5and R6are preferably, independently from each other, H, C1to C6alkyl, or, together with the C atoms to which they are attached, R5and R6form a C4to C7ring, preferably a C5ring. R5and R6may be both H. Together with the C atoms to which they are attached, R5and R6may form a C5ring. R5’is preferably -OY. Y is a C1to C20hydrocarbyl group, optionally containing up to two heteroatoms from Group 14-16 of the Periodic Table. Y may be C1-C10-hydrocarbyl, for example, linear or branched C1-C10-hydrocarbyl. Preferably Y is linear or branched C1-C6- alkyl, such as methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, or tert-butyl, C7-C10- arylalkyl, C7-C10-alkylaryl, or C6-C10-aryl, more preferably linear C1-C6-alkyl, branched C3-C6– alkyl, or C6-aryl, even more preferably linear C1-C4-alkyl, yet even more preferably methyl or ethyl, and most preferably methyl. R6’is a tertiary hydrocarbyl of the formula -CRx3, with Rxbeing a linear or branched C1 to C6 alkyl group, C3 to C8 cycloalkyl group or C6 to C10 aryl group. Preferably Rx’being linear C1- C3-alkyl; more preferably methyl. Thus advantageously, R6’ is tert-butyl. As will be apparent from a comparison of the structure of Formulae 1 and 2 above, for the indenyl group of Formula 1 having two Ar groups, each Ar group in Formula 2 is of the formula: For the indenyl group of Formula 1 having one Ar group, the Ar group in Formula 2 is of the formula: R3and R4may be, independently from each other, H; C1 to C20 hydrocarbyl, optionally containing up to two heteroatoms from Group 14-16 of the Periodic Table or wherein two adjacent R3or R4groups, together with the carbon atoms of the phenyl to which they are bound, form part of a C4 to C7 ring. Sensitivity: Internal Preferably, R3and R4are each independently, same or different from each other, H, linear or branched C1-C6-alkyl, C7-C20-arylalkyl, C7-C20-alkylaryl, C6-C20-aryl, -OR31, SR31, or N(R31)2, with R31being C1-C10-hydrocarbyl. More preferably, R3and R4are each independently, same or different from each other, H, linear or branched C1-C6-alkyl, for example, methyl or ethyl. Preferably, at least one R3per phenyl group and at least one R4is not H. Preferably, the Ar groups in Formula 2 have the formulae: wherein R3and R4are each independently, same or different from each other, linear or branched C1-C6-alkyl, C7-C20-arylalkyl, C7-C20-alkylaryl, C6-C20-aryl, -OR31, SR31, or N(R31)2, with R31being C1-C10-hydrocarbyl. More preferably, R3and R4are each independently, same or different from each other, linear or branched C1-C6-alkyl, for example, methyl, ethyl or tert-butyl. In a preferred embodiment, the C1-symmetric, bridged bisindenyl metallocene of the Formula (1) may meet the requirements of Formula (3) below. Sensitivity: Internal Mt, X, Y, R1, R2, R2’, R5, R6, R3’and R4may be defined as discussed in relation to Formula (2) above. More preferably: Mt is Zr or Hf, preferably Zr. Each X is preferably halogen, suitably F, Cl and Br, more preferably Cl. Each R1are preferably each independently selected from C1-C10-alkyl, more preferably C1-C6alkyl, most preferably, both R1are methyl. R2and R2’are preferably are each independently a C1to C6alkyl, for example, methyl, ethyl, n-propyl and i-propyl. R5and R6are preferably, independently from each other, H, C1 to C6 alkyl, or, together with the C atoms to which they are attached, R5and R6form a C4 to C7 ring, preferably a C5 ring. R5and R6may be both H. Together with the C atoms to which they are attached, R5and R6may form a C5ring. Y is preferably C1 to C6 alkyl, most preferably methyl. Preferably, R3and R4are each independently, same or different from each other, H or C1-C6- alkyl. Preferably, at least one R3per phenyl group and at least one R4is not H. More preferably, the R3and R4in the para position of the phenyl ring is H, while the R3and R4groups in the meta positions are C1-C6-alkyl, for example, methyl. Reaction with organometallic reagent As noted above, the starting C1-symmetric, bridged bisindenyl metallocene is reacted with organometallic reagent selected from an organolithium of the formula R”Li and a Grignard reagent of the formula RMg-X’, wherein R is C1 to C6 alkyl or benzyl, and X’ is halogen. The starting C1-symmetric, bridged bisindenyl metallocene is preferably reacted with at least 2 equivalents of the organometallic reagent selected from an organolithium of the formula R” - Li and a Grignard reagent of the formula RMg-X’, wherein R or R” are each independently H, C1 to C6 alkyl or benzyl, and X’ is halogen. The reaction results in the substitution of both X groups of the starting C1-symmetric, bridged bisindenyl metallocene with R from the Grignard reagent, RMg-X, or R” from the organolithium, R”Li; in addition the chirality of the complex is also inverted from syn to anti. Sensitivity: Internal The solvent, temperature and time of reaction may be selected to optimise syn- to anti- inversion of the metallocene complex. The reaction between the starting C1-symmetric, bridged bisindenyl metallocene and organometallic reagent may be carried out in the presence of a further epimerisation agent, for example, a halide salt. Suitable salts include an alkali metal, alkali earth metal or ammonium halide (e.g. lithium chloride or magnesium chloride). The salt may be produced as a byproduct of the preceding metallocene synthesis steps. In the organometallic reagent, RMg-X’, or R”Li: X’ is halogen, suitably F, Br, Cl or I, preferably Cl. R and R” are each independently selected from C1to C6alkyl or benzyl, preferably methyl. Preferably, the organometallic reagent is a Grignard reagent of the formula RMg-X’, wherein R is C1 to C6 alkyl or benzyl, and X’ is halogen. More preferably, X’ is Cl. More preferably, R is methyl. As discussed above, it is preferable that a mixture of the syn- and anti- isomers of the starting C1-symmetric, bridged bisindenyl metallocene is reacted with the organometallic reagent. A mixture may be used because the starting C1-symmetric, bridged bisindenyl metallocene may be synthesised as a mixture of syn- and anti- isomers. As discussed above, the syn-isomer of the C1-symmetric, bridged bisindenyl metallocene has the Formula (1) above. The anti-isomer of the C1-symmetric, bridged bisindenyl metallocene has the Formula (1’) below, with R1, R2, R2’, R5, R5’, R6, R6’, Ar, Mt and X as defined above in relation to Formula (1) above: Sensitivity: Internal Where the syn-isomer of the C1-symmetric, bridged bisindenyl metallocene has the Formula (2) above, the syn-isomer may be reacted with the organometallic reagent as a mixture that also includes the anti-isomer. For the avoidance of doubt, the anti-isomer of the compound of Formula (2) has the Formula (2’) below, where R1, R2, R2’, R3, R4, R5, R5’, R6, R6’, Mt and X are as defined in relation to Formula (2) above: Where the syn-isomer of the C1-symmetric, bridged bisindenyl metallocene has the Formula (3) above, the syn-isomer may be reacted with the organometallic reagent as a mixture that also includes the anti-isomer. For the avoidance of doubt, the anti-isomer of the compound of Formula (3) has the Formula (3’) below, where R1, R2, R2’, R3, R4, R5, R6, Mt and X are as defined in relation to Formula (3) above: Sensitivity: Internal Where a mixture of syn- and anti- isomers of the C1-symmetric, bridged bisindenyl metallocene is reacted with the organometallic reagent, the mixture of syn- and anti- isomers may have an anti-syn ratio of ≥ 1:99, for example, ≥ 10:90, ≥ 20:80, ≥ 30:70, ≥ 40:60 or ≥ 50:50. The mixture may have an anti / syn ratio of ≥ 55:45, preferably ≥ 60:40, more preferably ≥ 65:35, even more preferably, ≥ 70:30, for example, ≥ 75:25 or ≥ 80:20. Where a mixture of syn- and anti- isomers of the C1-symmetric, bridged bisindenyl metallocene that is reacted with the organometallic reagent the mixture of syn- and anti- isomers of the C1- symmetric, bridged bisindenyl metallocene that is reacted with the organometallic reagent may have an anti / syn ratio of ≤ 90:10, preferably ≤ 88:12. Where a mixture of syn- and anti- isomers of the C1-symmetric, bridged bisindenyl metallocene that is reacted with the organometallic reagent the mixture of syn- and anti- isomers of the C1-symmetric, bridged bisindenyl metallocene that is reacted with the organometallic reagent may have an anti / syn ratio of 1:99 to 95:5, for example, 10:90 to 95:5, 20:80 to 95:5, 30:70 to 95:5, 40:60 to 95:5 or 50:50 to 95:5. The mixture may have an anti / syn ratio of 55:45 to 90:10, preferably 60:40 to 90:10, more preferably 65:35 to 88:12, even more preferably, 70:30 to 88:12, for example, 75:25 or 80:20 to 88:12. The reaction between the syn-isomer of the starting C1-symmetric, bridged bisindenyl metallocene and organometallic reagent may be carried out in a suitable solvent, such as tetrahydrofuran (THF) or dibutylether. The reaction may be carried out at a suitable temperature, for example, at or above 50°C, preferably above 70°C, more preferably above 80°C. The reaction may be carried out at a temperature at or below 150°C, preferably below 130°C, more preferably below 110°C. The Sensitivity: Internal reaction may be carried out at 50 to 150°C, preferably 60 to 130°C, more preferably 70 to 110°C, for example at about 70 to 90°C. In some examples, the starting C1-symmetric, bridged bisindenyl metallocene is synthesised as a mixture of syn- and anti-isomers. It is this mixture that may be reacted with the organometallic reagent. This reaction may be a one-pot reaction with the organometallic agent being added to the product mixture of the synthesis step. It may not be necessary to isolate e.g. the syn-isomer for reaction with the organometallic reagent. Following the reaction between the starting C1-symmetric, bridged bisindenyl metallocene and the organometallic agent, solvent may be removed in a drying step. Thereafter, the product may be washed with an organic solvent, for example, pentane, hexane and / or toluene. Preferably pentane is used. Pentane may extract the syn-isomer, further increasing the relative proportion of the anti-isomer in the final product. Preferably, the organometallic reagent is reacted with the C1-symmetric, bridged bisindenyl metallocene in a greater than stoichiometric amount. The molar ratio organometallic reagent to metallocene is at least 2:1, or between 2:1 to 1:4, preferably 2:1 to 3:1. Bridged bisindenyl di(C1-6 alkyl) or di(benzyl) metallocene product As discussed above, the reaction between the starting C1-symmetric, bridged bisindenyl metallocene and the organometallic reagent produces a bridged bisindenyl di(C1-6 alkyl) metallocene or bridged bisindenyl di(benzyl) metallocene. The reaction preferably produces the anti-isomer of the bridged bisindenyl di(C1-6 alkyl) metallocene or bridged bisindenyl di(benzyl) metallocene. This anti-isomer has the Formula (4) below: Sensitivity: Internal R1, R2, R2’, R5, R5’, R6, R6’, Ar, and Mt are as defined above in relation to Formula (1) above. R is C1-6 alkyl or benzyl. R may be C1 to C5, C1 to C4 alkyl or C1 to C3 alkyl, or benzyl; more preferably methyl, ethyl or benzyl; most preferably methyl or benzyl. Preferably, R is methyl, ethyl or benzyl, more preferably methyl. Where a Grignard reagent, RMgX’, is used in the synthesis of the compound of Formula (4), R of Formula (4) is the same as R of the Grignard reagent. Where an organolithium of the formula R”Li is used to synthesise the compound of the Formula (4), R of Formula (4) is the same as R” of R”Li. In a preferred embodiment, the reaction may produce the anti-isomer of the bridged bisindenyl di(C1-6alkyl) metallocene or bridged bisindenyl di(benzyl) metallocene having the Formula (5) below. Sensitivity: Internal R1, R2, R2’, R3, R4, R5, R5’, R6, R6’and Mt are as defined in relation to Formula (2) above. R is C1-6 alkyl or benzyl. R may be C1 to C5, C1 to C4 alkyl or C1 to C3 alkyl, or benzyl; more preferably methyl, ethyl or benzyl; most preferably methyl or benzyl. Preferably, R is methyl, ethyl or benzyl, more preferably methyl. Where a Grignard reagent, RMgX’, is used in the synthesis of the compound of Formula (5), R of Formula (5) is the same as R of the Grignard reagent. Where an organolithium of the formula R”Li is used to synthesise the compound of the Formula (5), R of Formula (5) is the same as R” of R”Li. In a preferred embodiment, the reaction may produce the anti-isomer of the bridged bisindenyl di(C1-6 alkyl) metallocene or bridged bisindenyl di(benzyl) metallocene having the Formula (6) below. Sensitivity: Internal R1, R2, R2’, R3, R4, R5, R6, and Mt and X and Y are as defined in relation to Formula (3) above. R is C1-6 alkyl or benzyl. R may be C1 to C5, C1 to C4 alkyl or C1 to C3 alkyl, or benzyl; more preferably methyl, ethyl or benzyl; most preferably methyl or benzyl. Preferably, R is methyl, ethyl or benzyl, more preferably methyl. Where a Grignard reagent, RMgX’, is used in the synthesis of the compound of Formula (6), R of Formula (6) is the same as R of the Grignard reagent. Where an organolithium of the formula R”Li is used to synthesise the compound of the Formula (6), R of Formula (6) is the same as R” of R”Li. Examples of metallocene catalyst components produced in their anti-configuration include: MC1M MC2M MC3M MC4M Where a mixture of syn- and anti- isomers of the C1-symmetric, bridged bisindenyl metallocene is reacted with the organometallic reagent, the reaction produces a mixture of syn- and anti- isomers of a bridged bisindenyl di(C1-6 alkyl) metallocene or bridged bisindenyl di(benzyl) metallocene. Thus, the reaction may produce compounds of the formula (4), (5) and (6) in both the anti- and syn-form. Preferably, the mixtures produced Sensitivity: Internal have an anti / syn ratio that is greater than the anti / syn ratio of the mixture of syn- and anti- isomers of the C1-symmetric, bridged bisindenyl metallocene that is reacted with the organometallic reagent. More preferably, the ratio is at least 5% greater, even more preferably 10% greater than the anti / syn ratio of the starting mixture of syn- and anti- isomers of the C1-symmetric, bridged bisindenyl metallocene that is reacted with the organometallic reagent. When the C1-symmetric, bridged bisindenyl metallocene is reacted with the organometallic reagent, the reaction may result in a mixture of syn- and anti- isomers of a bridged bisindenyl di(C1-6alkyl) metallocene or bridged bisindenyl di(benzyl) metallocene. The latter mixture may have an anti-syn ratio that is ≥ 90:10, preferably ≥ 92:8, more preferably ≥ 95:5; even more preferably ≥ 97:3. Where the reaction produces a bridged bisindenyl di(C1-6alkyl) metallocene or a bridged bisindenyl di(benzyl) metallocene, the method may further comprise recovering the bridged bisindenyl di(C1-6 alkyl) metallocene or bridged bisindenyl di(benzyl) metallocene produced. This metallocene catalyst component may be used to form a polymerisation catalyst. The method may further comprise polymerising propylene and optionally at least one comonomer selected from ethylene and C4 to C10 alpha olefin comonomers with a catalyst formed using the metallocene catalyst component. The polymerisation may be carried out in the presence of a co-catalyst comprising a Group 13 element and optionally a support. Cocatalyst To form active catalytic species it is normally necessary to employ a cocatalyst as is well known in the art. Cocatalysts comprising one or more compounds of Group 13 metals, like organoaluminium, organoboron, and / or borate compounds used to activate metallocene catalysts are suitable for use in this invention. According to the present invention a cocatalyst system comprising an aluminoxane cocatalyst and optionally a boron containing cocatalyst is advantageously used in combination with the above defined metallocene complex . Preferably only cocatalysts comprising aluminium, like organoaluminium compounds used to activate metallocene catalysts, are utilized in this invention. Sensitivity: Internal In a preferred aspect of the present invention a cocatalyst system essentially consisting of, preferably consisting of, an aluminoxane cocatalyst is advantageously used in combination with the above defined metallocene complex. Thus, preferably no further cocatalysts comprising one or more compounds of Group 13 metals other than aluminium, like organoboron and / or borate compounds, used to activate metallocene catalysts are comprised in the polymerization catalyst. Suitable amounts of cocatalyst will be well known to the person skilled in the art. Preferably, the amount of cocatalyst is chosen to reach below defined molar ratios. The molar ratio of Al from the aluminoxane to the metal ion (Mt) (preferably zirconium) of the metallocene Al / Mt may be in the range 10:1 to 2000:1 mol / mol, preferably 50:1 to 1000:1, and more preferably 100:1 to 600:1 mol / mol. When a boron cocatalyst is used, the molar ratio of boron (B) to the metal ion (Mt) (preferably zirconium) of the metallocene B / Mt may be in the range 0.1:1 to 10:1 mol / mol, preferably 0.3:1 to 7:1, especially 0.5:1 to 3:1 mol / mol. Even more preferably, the molar ratio of feed amounts of boron (B) to metal ion (Mt), preferably zirconium, of the metallocene B / Mt is from 0.5:1 to 2:1 Aluminoxane cocatalyst The aluminoxane cocatalyst can be one of formula (A): where n is usually from 6 to 20 and R has the meaning below. Aluminoxanes are formed on partial hydrolysis of organoaluminium compounds, for example those of the formula AlR’3, AlR2Y’ and Al2R’3Y’3where R’ can be, for example, C1-C10-alkyl, preferably C1-C5-alkyl, or C3-C10-cycloalkyl, C7-C12-arylalkyl or -alkylaryl and / or phenyl or naphthyl, and where Y’ can be hydrogen, halogen, preferably chlorine or bromine, or C1-C10- alkoxy, preferably methoxy or ethoxy. The resulting oxygen-containing aluminoxanes are not in general pure compounds but mixtures of oligomers of the formula (A). Sensitivity: Internal The preferred aluminoxane is methylaluminoxane (MAO). Since the aluminoxanes used according to the invention as cocatalysts are not, owing to their mode of preparation, pure compounds, the molarity of aluminoxane solutions hereinafter is based on their aluminium content. Boron containing cocatalyst According to the present invention, the aluminoxane cocatalyst can be used in combination with a boron containing cocatalyst. It will be appreciated by the person skilled in the art that where boron based cocatalysts are employed, it is normal to pre-alkylate the complex by reaction thereof with an aluminium alkyl compound, such as TIBA. This procedure is well known and any suitable aluminium alkyl, e.g. Al(C1-C6alkyl)3can be used. Preferred aluminium alkyl compounds are triethylaluminium, tri-isobutylaluminium, tri-isohexylaluminium, tri-n-octylaluminium and tri- isooctylaluminium. Alternatively, when a borate cocatalyst is used, the metallocene complex is in its alkylated version, that is for example a dimethyl or dibenzyl metallocene complex can be used. Boron containing cocatalysts of interest include those of formula (B) BY”3 (B) wherein Y” is the same or different and is hydrogen, C1-C10-haloalkyl, or C6-C20-haloaryl, or fluorine, chlorine, bromine or iodine. Preferred examples for Y” are fluorine, trifluoromethyl, unsaturated groups such as haloaryl like p-fluorophenyl, 3,5-difluorophenyl, pentachlorophenyl, pentafluorophenyl, 3,4,5- trifluorophenyl and 3,5-di(trifluoromethyl)phenyl. Most preferably, Y” are fluorine, trifluoromethyl, aromatic fluorinated groups such as p- fluorophenyl, 3,5-difluorophenyl, pentafluorophenyl, 3,4,5-trifluorophenyl and 3,5- di(trifluoromethyl)phenyl. Preferred boron containing cocatalysts of formula (B) are trifluoroborane, tris(4- fluorophenyl)borane, tris(3,5-difluorophenyl)borane, tris(2,4,6-trifluorophenyl)borane, tris(penta-fluorophenyl)borane, and / or tris(3,4,5-trifluorophenyl)borane. Particular preference is given to tris(pentafluorophenyl)borane. Sensitivity: Internal However it is preferred that borates are used, i.e. compounds containing a borate anion. These compounds have formula (C): Z4B–-W+(C) wherein Z is a substituted phenyl derivative, said substituent being halo-C1-C6-alkyl or halogen; and W+is a cationic counterion. Preferably the substituents of Z are are fluoro or trifluoromethyl. Most preferably, the phenyl group is perfluorinated. The borate anion Z4B–is preferably a weakly-coordinating anion such as tetrakis(pentafluorophenyl)borate. Suitable cationic counterions W+are triarylcarbenium such as triphenylcarbenium or protonated amine or aniline derivatives such as methylammonium, anilinium, dimethylammonium, diethylammonium, N- methylanilinium, diphenylammonium, N,N-dimethylanilinium, trimethylammonium, triethylammonium, tri-n- butylammonium, methyldiphenylammonium, pyridinium, p-bromo-N,N- dimethylanilinium or p-nitro-N,N-dimethylanilinium. Preferred ionic compounds which can be used according to the present invention include: tributylammoniumtetra(pentafluorophenyl)borate, tributylammoniumtetra(trifluoromethylphenyl)borate, tributylammoniumtetra(4-fluorophenyl)borate, N,N-dimethylcyclohexylammoniumtetrakis(pentafluorophenyl)borate, N,N-dimethylbenzylammoniumtetrakis(pentafluorophenyl)borate, N,N-dimethylaniliniumtetrakis(pentafluorophenyl)borate, N,N-di(propyl)ammoniumtetrakis(pentafluorophenyl)borate, di(cyclohexyl)ammoniumtetrakist(pentafluorophenyl)borate, triphenylcarbeniumtetrakis(pentafluorophenyl)borate, or ferroceniumtetrakis(pentafluorophenyl)borate. Preference is given to triphenylcarbeniumtetrakis(pentafluorophenyl) borate, N,N- dimethylcyclohexylammoniumtetrakis(pentafluorophenyl)borate or N,N- dimethylbenzylammoniumtetrakis(pentafluorophenyl)borate. Mostly preferred are triphenylcarbeniumtetrakis(pentafluorophenyl) borate, N,N-dimethylaniliniumtetrakis(pentafluorophenyl)borate, N,N- dimethylcyclohexylammoniumtetrakis(pentafluorophenyl)borate, or N,N- dimethylbenzylammoniumtetrakis(pentafluorophenyl)borate. Sensitivity: Internal Catalyst Manufacture The metallocene catalysts can be used in supported or unsupported form. The particulate support material used is preferably an organic or inorganic material, such as silica, alumina or zirconia or a mixed oxide such as silica-alumina, in particular silica, alumina or silica- alumina. The use of a silica support is preferred. The skilled person is aware of the procedures required to support a metallocene catalyst. Especially preferably the support is a porous material so that the complex may be loaded into the pores of the support, e.g. using a process analogous to those described in WO94 / 14856, WO95 / 12622 and WO2006 / 097497. The particle size is not critical but is preferably in the range 5 to 200 μm, more preferably 20 to 80 μm. The use of these supports is routine in the art. Especially preferred procedures for producing such supported catalysts are those described in WO2020 / 239598, and WO2020 / 239603. In another embodiment, no external carrier is used but the catalyst is still presented in solid particulate form. Thus, no external support material, such as inert organic or inorganic carrier, for example silica as described above is employed. Such catalysts can be prepared as described for example in WO2003 / 051934, WO2014 / 060540, and WO2019 / 179959 The particulate support material used is an inorganic porous support such as a silica, alumina or a mixed oxide such as silica-alumina, in particular silica. The use of a silica support is preferred. The complex may be loaded into the pores of the particulate support, e.g. using a process analogous to those described in W094 / 14856, W095 / 12622, W02006 / 097497, and EP18282666. The average particle size of the support such as silica support can be typically from 10 to 100 µm. However, it has turned out that special advantages can be obtained, if the support has an average particle size from 15 to 80 µm, preferably from 18 to 50 µm. The average pore size of the inorganic porous support such as silica support can be in the range from 10 to 100 nm and the pore volume from 1 to 3 mL / g. The pore diameter of the inorganic porous support such as silica support can be in the range from 20 to 40 nm. Sensitivity: Internal The surface area of the inorganic porous support such as silica support can be typically in the range from 100 to 400 m2 / g. Examples of suitable support materials are, for instance, ES757 produced and marketed by PQ Corporation, Sylopol 948 produced and marketed by Grace or SUNSPERA DM-L-303 silica produced by AGC Si-Tech Co. Supports can be optionally calcined prior to the use in catalyst preparation in order to reach optimal silanol group content. The use of these supports is routine in the art. The catalyst can contain from 5 to 500 µmol, such as 10 to 100 µmol of transition metal of the metallocene per gram of support such as silica, and 3 to 15 mmol of Al per gram of support such as silica. The present polymerization catalyst may be produced by e.g. as described in WO2020 / 239603 or WO2020 / 239598. A polymerization catalyst containing such metallocenes may be produced by a process including the steps of P1-a) combining the porous inorganic support with a first portion of the aluminoxane cocatalyst in a hydrocarbon solvent to obtain aluminoxane cocatalyst treated support, optionally followed by thermal treatment of the aluminoxane treated support; P1-b) dissolving the metallocene complex in a hydrocarbon solvent, preferably an aromatic solvent, more preferably toluene, optionally adding a second portion of the aluminoxane cocatalyst in the hydrocarbon solvent optionally the boron containing cocatalyst wherein the amount of the first portion of the aluminoxane cocatalyst added in step a) is 75.0 to 100.0 wt% of the total amount of aluminoxane cocatalyst and the amount the second portion of the aluminoxane cocatalyst added in step b) is 0.0 to 25.0 wt% of the total amount of aluminoxane cocatalyst and the boron containing cocatalyst, when present, is added in an amount that a boron / M molar ratio of feed amounts in the range of 0.1 :1 to 10:1 is reached; P1-c) adding the solution obtained in step b) to the aluminoxane cocatalyst treated support obtained in step a) and optionally P1-d) drying the so obtained supported catalyst system. Sensitivity: Internal In step P1-b) of the process, the components can be mixed in any order. The optional boron containing cocatalyst can be mixed with the metallocene complex dissolved in the hydrocarbon solvent and followed by addition the optional aluminoxane, or the metallocene complex dissolved in the hydrocarbon solvent can be mixed with the optional aluminoxane and a hydrocarbon followed by addition of boron containing cocatalyst and so on. In some embodiments, all components might be combined simultaneously. Only one impregnation step is used, i.e. the treated support of step a) is loaded only in one step with the metallocene. In a preferred aspect of the present invention the process comprises P2-a) combining the porous inorganic support with aluminoxane cocatalyst in a hydrocarbon solvent to obtain aluminoxane cocatalyst treated support, optionally followed by thermal treatment of the aluminoxane treated support, filtering off the hydrocarbon solvent, optionally washing with an aromatic solvent, repeating the filtration and washing steps to remove unreacted aluminium compounds; drying the final aluminoxane cocatalyst treated support; P2-b) dissolving the metallocene in a hydrocarbon solvent optionally adding a methylaluminoxane cocatalyst in a hydrocarbon solvent, wherein the amount of methylaluminoxane cocatalyst added in step a) is 75.0 to 100.0 wt% of the total amount of methylaluminoxane cocatalyst and the amount of aluminoxane cocatalyst added in step b) is 0.0 to 25.0 wt% of the total amount of methylaluminoxane cocatalyst, to obtain a metallocene solution optionally comprising aluminoxane cocatalyst; P2-c) adding the metallocene solution to the aluminoxane cocatalyst treated support obtained in step a) and optionally P2-d) drying the so obtained supported catalyst system. If desired, the obtained supported catalyst system may be provided as an oil slurry with a desired solid content. The solid catalyst content in the slurry may be e.g. up to 30 wt%, like up to 25 wt%. The amounts of support, aluminoxane, preferably MAO, boron containing cocatalyst and metallocene depend on the desired herein defined ratios (boron / M, Al / M, Al / SiO2, M / SiO2). Polymers It is a feature of the invention that the claimed process enables the formation of polypropylene with very high melting point. These features can be achieved at commercially interesting polymerization temperatures, e.g.60 °C or more, such as from 60 °C to 90 °C. The polydispersity index (Mw / Mn) of the polymers depend on the polymerization conditions Sensitivity: Internal in each reactor, and can be between 2.0 and 7.0. In a particular embodiment, the propylene polymers obtained using the catalysts of the invention have a narrow polydispersity index (Mw / Mn), between 2.0 and 4.0. Propylene copolymers Propylene copolymers with ethylene or with C4-C10alpha olefin comonomers, preferably propylene terpolymers with ethylene and with C4-C10alpha olefin comonomers, more preferably propylene-ethylene-butene terpolymers, made by the process of the invention can be made with high productivity. The productivity of the polymerization process may be at least 13 kg of polymer per gram of catalyst, preferably at least 14 kg of polymer per gram of catalyst, more preferably at least 14.5 kg polymer per gram of catalyst. The polymerization temperature may be above 60°C, preferably above 65°C. The process of the invention may be used to produce propylene copolymers, preferably propylene terpolymers, having relatively low MFR2. For example, the MFR2 may below 15, preferably below 10 and, for example, below 8. When such copolymers are produced in liquid monomers, the MFR2 may be below 10, preferably below 8. The propylene copolymers may have a total comonomer content of 0.5 to 10 weight %, preferably 1 to 8 weight %, for example, 2 to 7 weight %. For example, the propylene copolymer may be a terpolymer having an ethylene content of 0.5 to 2 weight %, and a C4- C10 alpha olefin comonomer content of 4 to 8 weight %. The propylene copolymer may be a terpolymer having an ethylene content of 0.8 to 1.8 weight %, and a C4-C10 alpha olefin comonomer content of 4.5 to 7 weight %. The propylene copolymer may be a terpolymer having an ethylene content of 0.9 to 1.5 weight %, and a C4-C10 alpha olefin comonomer content of 4.8 to 6.5 weight %. The propylene copolymer may be a terpolymer having an ethylene content of 1.0 to 1.3 weight %, and a C4-C10 alpha olefin comonomer content of 5.0 to 6.0 weight %. In one embodiment, the propylene copolymer may be a terpolymer having an ethylene content of 0.8 to 1.8 weight %, and a C4 alpha olefin comonomer content of 4.5 to 7 weight %. The propylene copolymer may be a terpolymer having an ethylene content of 0.9 to 1.5 weight %, and a C4 alpha olefin comonomer content of 4.8 to 6.5 weight %. The propylene copolymer may be a terpolymer having an ethylene content of 1.0 to 1.3 weight %, and a C4 alpha olefin comonomer content of 5.0 to 6.0 weight %. In some examples, the propylene copolymer is a terpolymer having an ethylene content and C4-C10alpha olefin comonomer (e.g. C4alpha olefin comonomer) content as described above in combination with an MFR2may below 15, preferably below 10 and, for example, Sensitivity: Internal below 8. An advantage of certain embodiments of the present disclosure is that propylene copolymers having such MFR2properties may be produced at desirable levels of productivity. Preferably, such propylene copolymers may be produced at relatively high levels of productivity, for example, of at least 13 kg of polymer per gram of catalyst, preferably at least 14 kg of polymer per gram of catalyst, more preferably at least 14.5 kg polymer per gram of catalyst. The polymers made by the catalysts of the description are useful in all kinds of end articles such as pipes, films (cast, blown or BOPP films, such as for example BOPP for capacitor film), fibers (such as spun-bond and melt-blown fibers), moulded articles (e.g. injection moulded, blow moulded, rotomolded articles), extrusion coatings and so on. The invention will now be illustrated by reference to the following non-limiting Examples. EXPERIMENTAL Sensitivity: Internal Example 1 In this Example, dimethylsilanediyl[2-methyl-4,8-di(3,5-dimethylphenyl)-1,5,6,7-tetrahydro-s-indacen- 1-yl][2-methyl-4-(3,5-dimethylphenyl)-5-methoxy-6-tert-butylinden-1-yl]zirconium dichloride (MC1) is prepared and converted into dimethylsilanediyl[2-methyl-4,8-di(3,5-dimethylphenyl)-1,5,6,7- tetrahydro-s-indacen-1-yl][2-methyl-4-(3,5-dimethylphenyl)-5-methoxy-6-tert-butylinden-1- yl]zirconium dimethyl (MC1M). Synthesis of the ligand 6-tert-butyl-5-methoxy-2-methylindan-1-one Methacrylic acid (137.6 g, 1.6 mol) was added to Eaton's reagent obtained from 220 g of P4O10and 1120 ml of MeSO3H at 50 °C. To this mixture, 1-tert-butyl-2-methoxybenzene (131.2 g, 0.8 mol) was added dropwise by vigorous stirring over ca.1 h at 50-53 °C (water bath temperature). The resulting mixture was stirred for 1 h at this temperature, then cooled to room temperature, and poured onto a mixture of 1.5 liter of cold water and 3 kg of ice. The crude product was extracted with 3 ^600 ml of dichloromethane. The combined organic extract was washed by aqueous K2CO3, dried over K2CO3and then evaporated to dryness. Fractional rectification of the residue gave 159.5 g of yellowish oil (bp 150-180oC / 5 mm Hg.) which crystallizes at room temperature. Further on, this product was dissolved in 300 ml of hot hexanes. Crystals precipitated from this solution overnight at room temperature were collected, washed with 50 ml of cold hexanes, and dried under vacuum. This procedure gave 127.0 g of the pure 6-tert-butyl-5-methoxy-2-methylindan-1-one. The mother liquor was evaporated to ca.100 ml that resulted in formation of one portion of the crystalline product. This procedure gave additional 10.5 g of the title product. Thus, the total yield of the product was 137.5 g (74%). 2-methyl-4-bromo-5-methoxy-6-tert-butyl-indan-1-one O Sensitivity: Internal Bromine (45.0 g, 0.282 mol) was added over ca.5 min with vigorous stirring into a mixture of 60.0 g (0.258 mol) of 6-tert-butyl-5-methoxy-2-methylindan-1-one, 130 g of NaOAc(H2O)3, 1.5 g of Et4NI, 220 ml of dichloromethane, and 450 ml of water cooled to 5 °C. This mixture was stirred for 1 h at 5 °C, then a solution of 60.0 g of NaOAc(H2O)3in 200 ml of water was added. To the resulting mixture, bromine (23.5 g, 0.147 mmol) was added at 5 °C. The resulting solution was stirred for 30 min and then washed by aqueous Na2SO3. The crude product was extracted with 3 ^300 ml of dichloromethane. The combined organic extract was dried over K2CO3, passed through short layer of silica gel 60 (40-63 µm) and then evaporated to dryness. The residue was dried in vacuum to give 79.9 g (99%) of the target product which was used without further purification.1H NMR (CDCl3): δ 7.70 (s, 1H), 4.03 (s, 3H), 3.31 (dd, J = 17.4 Hz, J = 7.8 Hz, 1H), 2.72 (m, 1H), 2.62 (dd, J = 17.4 Hz, J = 3.8 Hz, 1H), 1.40 (s, 9H), 1.32 (d, J = 7.6 Hz, 3H).13C{1H} NMR (CDCl3): δ 208.0, 162.8, 154.0, 145.5, 132.7, 121.5, 116.7, 61.7, 42.2, 36.1, 35.7, 30.6, 16.4. 2-methyl-4-(3,5-dimethylphenyl)-5-methoxy-6-tert-butyl-indan-1-one O A mixture of 49.14 g (157.9 mmol) of 2-methyl-4-bromo-5-methoxy-6-tert-butyl-indan-1-one, 29.6 g (197.4 mmol, 1.25 eq.) of (3,5-dimethylphenyl)boronic acid, 45.2 g (427 mmol) of Na2CO3, 1.87 g (8.3 mmol, 5 mol.%) of Pd(OAc)2, 4.36 g (16.6 mmol, 10 mol.%) of PPh3, 200 ml of water, and 500 ml of 1,2-dimethoxyethane was refluxed for 6.5 h. DME was evaporated on a rotary evaporator, 600 ml of water and 700 ml of dichloromethane were added to the residue. The organic layer was separated, and the aqueous one was additionally extracted with 200 ml of dichloromethane. The combined extract was dried over K2CO3and then evaporated to dryness to give black oil. Crude product was purified by flash chromatography on silica gel 60 (40-63 µm, hexane-dichloromethane = 1:1, vol., then, 1:3, vol.) to give 48.43 g (91%) of 2-methyl-4-(3,5-dimethylphenyl)-5-methoxy-6- tert-butyl-indan-1-one as a brownish oil. Anal. calc. for C23H28O2: C, 82.10; H, 8.39. Found: C, 82.39; H, 8.52.1H NMR (CDCl3): δ 7.73 (s, 1H), 7.02 (s, 3H), 7.01 (s, 3H), 3.32 (s, 3H), 3.13 (dd, J = 17.5 Hz, J = 7.8 Hz, 1H), 2.68-2.57 (m, 1H), 2.44 (dd, J = 17.5 Hz, J = 3.9 Hz), 2.36 (s, 6H), 1.42 (s, 9H), 1.25 (d, J = 7.5 Hz, 3H).13C{1H} NMR (CDCl3): δ 208.90, 163.50, 152.90, 143.32, 138.08, 136.26, 132.68, 130.84, 129.08, 127.18, 121.30, 60.52, 42.17, 35.37, 34.34, 30.52, 21.38, 16.40. 2-methyl-5-tert-butyl-6-methoxy-7-(3,5-dimethylphenyl)-1H-indene Sensitivity: Internal NaBH4(8.2 g, 217 mmol) was added to a solution of 2-methyl-4-(3,5-dimethylphenyl)-5-methoxy-6- tert-butyl-indan-1-one (48.43 g, 143.9 mmol) in 300 ml of THF cooled to 5°C. Then, 150 ml of methanol was added dropwise to this mixture with vigorous stirring over ca.7 h at 5°C. The resulting mixture was evaporated to dryness, and the residue wad partitioned between 500 ml of dichloromethane and 500 ml of 2 M HCl. The organic layer was separated, the aqueous layer was additionally extracted with 100 ml of dichloromethane. The combined organic extract was evaporated to dryness to give a slightly yellowish oil. To a solution of this oil in 600 ml of toluene, 400 mg of TsOH was added, then this mixture was refluxed with Dean-Stark head for 10 min and then cooled to room temperature using water bath. The formed solution was washed with 10% Na2CO3, the organic layer was separated, the aqueous layer was extracted with 150 ml of dichloromethane. The combined organic extract was dried over K2CO3 and then passed through a short layer of silica gel 60 (40-63 µm). The silica gel layer was additionally washed with 100 ml of dichloromethane. The combined organic elute was evaporated to dryness, and the resulting oil was dried under vacuum at elevated temperature. This procedure gave 45.34 g (98%) of 2-methyl-5-tert- butyl-6-methoxy-7-(3,5-dimethylphenyl)-1H-indene which was further used without an additional purification. Anal. calc. for C23H28O: C, 86.20; H, 8.81. Found: C, 86.29; H, 9.07.1H NMR (CDCl3): δ 7.20 (s, 1H), 7.08 (br.s, 1H), 6.98 (br.s, 1H), 6.42 (m, 1H), 3.25 (s, 3H), 3.11 (s, 2H), 2.36 (s, 6H), 2.06 (s, 3H), 1.43 (s, 9H).13C{1H} NMR (CDCl3): δ 154.20, 145.22, 141.78, 140.82, 140.64, 138.30, 137.64, 131.80, 128.44, 127.18, 126.85, 116.98, 60.65, 42.80, 35.12, 31.01, 21.41, 16.65. [6-tert-butyl-4-(3,5-dimethylphenyl)-5-methoxy-2-methyl-1H-inden-1-yl] chlorodimethylsilane nBuLi in hexanes (2.43 M, 14.6 ml, 35.5 mmol) was added in one portion to a solution of 5-tert-butyl- 7-(3,5-dimethylphenyl)-6-methoxy-2-methyl-1H-indene (11.3 g, 35.3 mmol) in 200 ml of ether cooled to –50 °C. The resulting orange solution was stirred overnight at room temperature, then the obtained orange solution containing a yellowish precipitate was cooled to –78 °C (the precipitate Sensitivity: Internal almost completely disappeared), and dichlorodimethylsilane (22.8 g, 177 mmol, 5 equiv) was added in one portion. The formed solution was warmed to room temperature and stirred overnight at room temperature. The resulting mixture was filtered through glass frit (G4 mesh size). The precipitate was additionally washed with 2x10 ml of ether. The combined filtrate was evaporated to dryness to give the title material as slightly orange oil which was used without further purification. Step 1: anti / syn-dimethylsilanediyl[2-methyl-4,8-di(3,5-dimethylphenyl)-1,5,6,7-tetrahydro-s-indacen- 1-yl][2-methyl-4-(3,5-dimethylphenyl)-5-methoxy-6-tert-butylinden-1-yl]zirconium dichloride Note that in the particular reaction scheme above the anti-isomer is depicted. However, the metallocene is formed as a mixture of anti- and syn-isomers (anti / syn = 85:15).nBuLi in hexanes (2.5 M, 8.5 ml, 21.25 mmol) was added in one portion at room temperature to a yellowish solution of [2-methyl-4,8-bis(3,5-dimethylphenyl)-1,5,6,7-tetrahydro-s-indacen-1-yl][2- methyl-4-(3,5-dimethyl-phenyl)-5-methoxy-6-tert-butyl-1H-inden-1-yl]dimethylsilane (8.0 g, 10.59 mmol) in 50 ml ofnBu2O. This mixture was stirred for 17 h at room temperature, the resulting red solution was cooled in an ice bath, and then ZrCl4 (2.47 g, 10.6 mmol) was added. The reaction mixture was stirred for ca.3 h at 0 °C, then for 24 h at room temperature to give an orange suspension: red solution with orange precipitate. This suspension was evaporated to dryness to give a solid residue, containing MC1 in a 85:15 anti / syn ratio. Step 2: anti-dimethylsilanediyl[2-methyl-4,8-di(3,5-dimethylphenyl)-1,5,6,7-tetrahydro-s-indacen-1- yl][2-methyl-4-(3,5-dimethylphenyl)-5-methoxy-6-tert-butylinden-1-yl]zirconium dimethyl Sensitivity: Internal anti / syn=85:15 anti MeMgCl in THF (1.68 M, 15.0 ml, 25.2 mmol, 2.38 equiv.) was added to the solid residue, and the obtained mixture was stirred for 24 h at 90 °C. The resulting suspension was evaporated to dryness, and the precipitate was extracted with 2x40 ml of n-pentane at room temperature (Note: after addition of pentane, the resulting mixture was stirred for 10 min). The solid residue after the above two extractions with pentane was dried under vacuum and then extracted with 6x50ml of boiling hexane. The combined extract was evaporated, and the residue was dried under vacuum to give 6.2 g of pure MC1M (yield 71%). Example 2 In this Example, dimethylsilanediyl[2-methyl-4,8-di(3,5-dimethylphenyl)-1,5,6,7-tetrahydro-s-indacen- 1-yl][2-methyl-4-(3,5-dimethylphenyl)-5-methoxy-6-tert-butylinden-1-yl]zirconium dimethyl, (MC1M) is produced from dimethylsilanediyl[2-methyl-4,8-di(3,5-dimethylphenyl)-1,5,6,7-tetrahydro-s- indacen-1-yl][2-methyl-4-(3,5-dimethylphenyl)-5-methoxy-6-tert-butylinden-1-yl]zirconium dichloride (MC1) with a modified purification step. Step 1: anti / syn-dimethylsilanediyl[2-methyl-4,8-di(3,5-dimethylphenyl)-1,5,6,7-tetrahydro-s-indacen- anti / syn=85:15 Sensitivity: Internal Note that in the particular reaction scheme above the anti-isomer is depicted. However, the metallocene is formed as a mixture of anti- and syn-isomers (anti / syn = 85:15). nBuLi in hexanes (2.5 M, 8.5 ml, 21.25 mmol) was added in one portion to a yellowish solution of [4,8- bis(3,5-dimethylphenyl)-2-methyl-1,5,6,7-tetrahydro-s-indacen-1-yl][6-tert-butyl-4-(3,5-dimethyl- phenyl)-5-methoxy-2-methyl-1H-inden-1-yl]dimethylsilane (8.0 g, 10.59 mmol) in 50 ml ofnBu2O at room temperature. This mixture was stirred for 17 h at room temperature giving a red solution. This solution was cooled in an ice bath, then ZrCl4(2.47 g, 10.6 mmol) was added to it. The reaction mixture was stirred for ca. 30 min at 0 °C, then for 24 h at room temperature to give an orange suspension: red solution with orange precipitate. This suspension was evaporated to dryness (anti / syn ca.85 / 15). Step 2: anti-dimethylsilanediyl[2-methyl-4,8-di(3,5-dimethylphenyl)-1,5,6,7-tetrahydro-s-indacen-1- anti / syn=85:15 anti MeMgCl in THF (1.68 M, 15.1 ml, 25.37 mmol, 2.4 equiv) was added to the above solid residue, and the obtained mixture was stirred for 21.5 h at 90 °C. The resulting suspension was evaporated to dryness, and the so obtained solid residue was stirred with 40 ml of n-pentane for 15 min at room temperature, then this suspension was filtered through glass frit (G3), and the filter cake was additionally washed with 15 ml of n-pentane. The filter cake and the filtrate were analyzed by1H NMR spectroscopy. m, g anti / syn ratio Filter cake - 100% anti Filtrate (residue after 2.16 80:20 evaporation) Sensitivity: Internal The filter cake was extracted with 3 ^100 ml of boiling n-hexane, the combined extract was evaporated to dryness, and the residue was dried under vacuum to give 6.51 g of pure anti-MC1M as a yellowish solid (Yield 70.3 wt%). Example 3 In this Example, dimethylsilanediyl[2-methyl-4,8-di(3,5-dimethylphenyl)-1,5,6,7-tetrahydro-s- indacen-1-yl][2-methyl-4-(3,5-dimethylphenyl)-5-methoxy-6-tert-butylinden-1-yl]hafnium dimethyl, (MC2M) is produced from dimethylsilanediyl[2-methyl-4,8-di(3,5-dimethylphenyl)-1,5,6,7-tetrahydro- s-indacen-1-yl][2-methyl-4-(3,5-dimethylphenyl)-5-methoxy-6-tert-butylinden-1-yl]hafnium dichloride (MC2) Step 1: anti / syn-dimethylsilanediyl[2-methyl-4,8-di(3,5-dimethylphenyl)-1,5,6,7-tetrahydro-s-indacen- 1-yl][2-methyl-4-(3,5-dimethylphenyl)-5-methoxy-6-tert-butylinden-1-yl]hafnium dichloride anti / syn=87:13 Note that in the particular reaction scheme above the anti-isomer is depicted. However, the metallocene is formed as a mixture of anti- and syn-isomers (anti / syn = 87:13).nBuLi in hexanes (2.5 M, 8.5 ml, 21.25 mmol) was added in one portion to a yellowish solution of [4,8- bis(3,5-dimethylphenyl)-2-methyl-1,5,6,7-tetrahydro-s-indacen-1-yl][6-tert-butyl-4-(3,5-dimethyl- phenyl)-5-methoxy-2-methyl-1H-inden-1-yl]dimethylsilane (8.0 g, 10.59 mmol) in 50 ml ofnBu2O at room temperature. This mixture was stirred for 17 h at room temperature to give a red solution. This solution was cooled in an ice bath, then HfCl4(3.39 g, 10.58 mmol) was added. The reaction mixture was stirred for ca.1 h at 0 °C, then for 24 h at room temperature to give a red solution with yellow Sensitivity: Internal precipitate. This suspension was evaporated to dryness to give a solid residue (anti / syn ca.87 / 13 and byproducts). Step 2: anti-dimethylsilanediyl[2-methyl-4,8-di(3,5-dimethylphenyl)-1,5,6,7-tetrahydro-s-indacen-1- yl][2-methyl-4-(3,5-dimethylphenyl)-5-methoxy-6-tert-butylinden-1-yl]hafnium dimethyl MeMgCl in THF (1.68 M, 15.0 ml, 25.2 mmol, 2.38 equiv) was added to the above solid, and the obtained mixture was stirred for 20 h at 90 °C. The resulting suspension was evaporated to dryness, and the crude mixture was extracted with 3 ^40 ml of boiling n-pentane: after addition of each portion of pentane, the resulting mixture was stirred for 5 min, then filtered, the filtrate was evaporated to dryness, and the residue was analyzed by NMR spectroscopy. The results are shown in the table below: g anti / syn ratio reaction mixture 98 / 2 + by- products 1st extraction (40 ml of warm n- 2.9 96 / 4 + by- pentane) products 2nd extraction (40 ml of warm n- 1.2 96 / 4 + by- pentane) products 3rdextraction (40 ml of warm n- 0.7 98 / 2 + by- pentane) products The solid residue remaining after three extractions with pentane was extracted with 200 ml of boiling hexane. The obtained solution (after filtration) was evaporated to dryness, and the residue was dried under vacuum to give 3.9 g of pure MC2M. To the combined solid residues obtained after evaporation Sensitivity: Internal of the 1st, 2nd, and 3rd pentane extracts (i.e.2.9 g, 1.2 g and 0.7 g samples from the table above) 30 ml of n-pentane was added, and the resulting suspension was stirred for 2 h at room temperature. The precipitate was filtered off (G4) and dried under vacuum to give 1.4 g of MC2M. Thus, the total yield of MC2M isolated in this synthesis was 5.3 g (52.0%). Example 4 In this Example, dimethylsilanediyl[2-methyl-4,7-bis(3,5-dimethylphenyl)-inden-1-yl][2-methyl-4-(3,5- dimethylphenyl)-5-methoxy-6-tert-butylinden-1-yl] zirconium dichloride, MC3, was prepared. This was then converted into dimethylsilanediyl[2-methyl-4,7-bis(3,5-dimethylphenyl)-inden-1-yl][2- methyl-4-(3,5-dimethylphenyl)-5-methoxy-6-tert-butylinden-1-yl] dimethyl zirconium, MC3M. Synthesis of the ligand: 1,4-Dibromo-2-(bromomethyl)benzene Br Bromine (15.5 ml, 47.9 g, 0.30 mmol) was added dropwise to 2,5-dibromotoluene (74.9 g, 0.30 mol) with vigorous stirring over 3 h at 200 °C. The resulting mixture was cooled to room temperature. Fractional distillation gave a colorless liquid, b.p.132°C - 135°C / 3 mm Hg. Yield 84.3 g (85%, ca. 82% purity).1H NMR (CDCl3): δ 7.59 (s, 1H), 7.43 (d, J = 8.5 Hz, 1H), 7.29 (d, J = 8.5 Hz, 1H), 4.52 (s, 2H).13C NMR (CDCl3): δ 138.94, 134.64, 133.95, 133.04, 130.31, 121.44, 32.11. 4,7-Dibromo-2-methylindan-1-one 1. NaCMe(COOEt)22. KOH, H2O, EtOH 3.HCl O Sodium metal (6.10 g, 0.27 mol) was dissolved in 200 ml of dry ethanol. To the resulting solution, 45.5 g (0.26 mol) of diethylmethylmalonate was added. This mixture was stirred for 15 min, then 84.3 g (0.26 mol) of 1,4-dibromo-2-(bromomethyl)benzene was added at a rate that allowed the reaction mixture to maintain a gentle reflux. Additionally, this mixture was refluxed for 4 h, then Sensitivity: Internal cooled to room temperature. A solution of 52.1 g of KOH in 140 ml of water was added. This mixture was refluxed for 6 h to saponificate the ester formed. Ethanol was distilled off. To the residue 200 ml of water and then 12 M HCl were added to pH=1. The substituted methylmalonic acid precipitated was filtered off, washed with 2x100 ml of cold water, and dried on air. Crude 3-(2,5-dibromophenyl)- 2-methylpropanoic acid was obtained after decarboxylation of this substituted methylmalonic acid by heating the latter in a round bottom flask for 0.5 h at 180°C. The so obtained crude 3-(2,5- dibromophenyl)-2- methylpropanoic acid was used without further purification. A mixture of this acid, 70 ml (114.6 g, 0.96 mol) of SOCl2, and 100 ml of dichloromethane was stirred overnight at room temperature. Excess thionyl chloride and dichloromethane were distilled off. The residue was dried in vacuum and then dissolved in 95 ml of dichloromethane. The obtained solution was added dropwise for 1 h to a suspension of 47.0 g (0.35 mol) of AlCl3in 470 ml of dichloromethane at 0 °C. The formed mixture was refluxed for 3 h, cooled to ambient temperature, and then poured onto 1000 cm3of ice. The organic layer was separated. The aqueous layer was extracted with 3x200 ml of dichloromethane. The combined organic extract was dried over K2CO3and evaporated to dryness. The crude 4,7-dibromo-2-methylindan-1-one was purified by column chromatography on silica gel 60 (40-63 µm, d 50 mm, l 1250 mm, eluent: hexanes / CH2Cl2 = 1:1, vol.). Yield 54.1 g (70%).1H NMR (CDCl3): δ 7.52 (d, J= 8.4 Hz, 1H), 7.37 (d, J= 8.4 Hz, 1H), 3.27 (dd, J= 17.7 Hz, J= 8.0 Hz, 1H), 3.73 (m, 1H), 2.58 (dd, J= 17.7 Hz, J= 4.2 Hz, 1H), 1.31 (d, J= 7.3 Hz, 3H).13C NMR (CDCI3): δ 205.5, 155.4, 137.6, 135.3, 133.9, 121.0, 118.6, 42.6, 35.3, 16.1. 4,7-Dibromo-2-methyl-1H-indene NaBH4(9.40 g, 0.248 mmol) was added to a solution of 4,7-dibromo-2-methyl-1-indanone (54.1 g, 0.178 mol) in 200 ml of THF cooled to 5 °C. Then, 80 ml of methanol was added dropwise to this mixture over ca.3 h at 5 °C. The obtained mixture was stirred overnight at ambient temperature. The resulting mixture was evaporated to dryness, and the residue was partitioned between 500 ml of dichloromethane and 500 ml of 2 M HCl. The organic layer was separated, the aqueous layer was additionally extracted with 100 ml of dichloromethane. The combined organic extract was evaporated to dryness. To the residue 500 ml of toluene and 5.0 g TsOH were added. This toluene solution was refluxed with Dean-Stark head until elimination of water was complete. After cooling to room temperature the reaction mixture was washed with 200 ml of 10% NaHCO3. The organic layer was separated, and the aqueous layer was additionally extracted with 2 ^50 ml of toluene. The Sensitivity: Internal combined organic extract was dried over K2CO3and evaporated to dryness. The product was purified by flash-chromatography on silica gel 60 (40-63 µm, d 50 mm, l 550 mm, eluent: hexanes / CH2Cl2= 10:1, vol.). Yield 47.2 g (92%).1H NMR (CDCl3): δ 7.18 (d, J= 8.4 Hz, 1H), 7.03 (d, J= 8.4 Hz, 1H), 6.55 (s, 1H), 3.29 (s, 2H), 2.14 (s, 3H).13C NMR (CDCI3): δ 148.17, 146.88, 144.28, 131.09, 127.88, 126.85, 116.93, 112.61, 45.38, 16.73. 4,7-Bis(3,5-dimethylphenyl)-2-methyl-1H-indene A mixture of 46.79 g (162.48 mmol) of 4,7-dibromo-2-methyl-1H-indene, 56.0 g (370 mmol) of (3,5- dimethylphenyl)boronic acid, 93.1 g (906 mmol) of Na2CO3, 1.3 g (2.54 mmol) of Pd(PtBu3)2, 420 ml of water, and 600 ml of 2-methyltetrahydrofuran was refluxed for 5 h. The organic layer was separated and evaporated to dryness. The crude 4,7-bis(3,5-dimethylphenyl)-2-methyl-1H-indene was purified by column chromatography on silica gel 60 (40-63 µm, d 50 mm, l 1000 mm, eluent: hexanes / CH2Cl2 = 5:1, vol.). The elute was evaporated to dryness, and the residue was refluxed with 300 ml of hot n-hexane. White crystals precipitated at –5 °C were collected and dried under vacuum. This procedure gave 52.5 g (95%) of the title product.1H NMR (CDCl3): δ 7.31 (d, J= 7.8 Hz, 1H), 7.17-7.15 (m, 5H), 7.00 (s, 2H), 6.72-6.70 (m, 1H), 3.43 (s, 2H), 2.39-2.38 (m, 12H), 2.13 (s, 3H).13C NMR (CDCI3): δ 146.50, 143.78, 141.23, 141.19, 140.94, 137.82, 136.43, 133.20, 128.65, 128.40, 127.41, 126.74, 126.34, 126.32, 124.64, 43.06, 21.42, 16.82. [4,7-Bis(3,5-dimethylphenyl)-2-methyl-1H-inden-1-yl]-[6-tert-butyl-4-(3,5-dimethylphenyl)-5- methoxy-2-methyl-1H-inden-1-yl]dimethylsilane Sensitivity: InternalnBuLi in hexanes (2.5 M, 6.0 ml, 15.0 mmol) was added in one portion to a solution of 4,7-bis(3,5- dimethylphenyl)-2-methyl-1H-indene (5.09 g, 15.0 mmol) in a mixture of 80 ml of ether and 40 ml of THF cooled to –50 °C. The resulting mixture was stirred overnight at room temperature, then the so obtained yellow suspension was cooled to –50 °C, and 150 mg of CuCN was added. The obtained mixture was stirred for 0.5 h at –15 °C, then a solution of [6-tert-butyl-4-(3,5-dimethylphenyl)-5- methoxy-2-methyl-1H-inden-1-yl]chlorodimethylsilane (6.2 g, 15.0 mmol) in 125 ml of ether was added in one portion. The resulting mixture was stirred overnight at room temperature, then filtered through a pad of silica gel 60 (40-63 µm) which was additionally washed with 2x50 ml of ether. The combined organic elute was evaporated to dryness. The product was purified by flash chromatography on silica gel 60 (40-63 µm, 600 ml, eluent: hexanes: dichloromethane = 5:1, vol.). The combined organic elute was evaporated to dryness, and the residue was dried under vacuum at elevated temperature to give 9.4 g (13.15 mmol, yield ca.87.6%, purity ca.92%) of the title product (as a ca 55:45 mixture of the stereoisomers) as a slightly yellowish glassy solid. Synthesis of metallocenes MC3 and MC3M dimethylsilanediyl[2-methyl-4,7-bis(3,5-dimethylphenyl)-inden-1-yl][2-methyl-4-(3,5- -5- 6-tert- 1- zirconium dichloride anti / syn=81:19 Sensitivity: Internal Note that in the particular reaction scheme above the anti-isomer is depicted. However, the metallocene is formed as a mixture of anti- and syn-isomers (anti / syn = 81:19).nBuLi in hexanes (2.5 M, 10.15 ml, 25.44 mmol) was added in one portion to a solution of [4,7- bis(3,5-dimethylphenyl)-2-methyl-1H-inden-1-yl][6-tert-butyl-4-(3,5-dimethylphenyl)-5-methoxy-2- methyl-1H-inden-1-yl]dimethylsilane (9.1 g, 12.72 mmol) in 90 ml of di-n-butyl ether at room temperature. This mixture was stirred overnight at room temperature, then the resulting red solution was cooled to 0 °C in an ice-bath, and ZrCl4(2.96 g, 12.71 mmol) was added. The reaction mixture was stirred for 24 h at room temperature to give a yellow suspension. This suspension was evaporated to dryness. On the evidence of NMR spectroscopy, the obtained product included a ca. 81:19 mixture of anti- and syn-zirconocene dichlorides. Step 2: anti-dimethylsilanediyl[2-methyl-4,7-bis(3,5-dimethylphenyl)-inden-1-yl][2-methyl-4-(3,5- dimethylphenyl)-5-methoxy-6-tert-butylinden-1-yl] zirconium dimethyl MeMgCl in THF (1.68 M, 18.16 ml, 30.5 mmol, 2.4 equiv.) and 10 ml of THF (necessary for obtaining a homogeneous solution at 90 °C) were added to the solid residue originated in the previous step, and the obtained mixture was stirred for 21.5 h at 90 °C. The resulting suspension was evaporated to dryness, and the so obtained solid residue was stirred with 50 ml of n-pentane for 15 min at room temperature, then this suspension was filtered through glass frit (G3), and the filter cake was additionally washed with 20 ml of n-pentane. The filter cake and the filtrate were analyzed by1H NMR spectroscopy. weight, g anti / syn- ratio Filter cake - only anti Filtrate (residue after 0.6 anti, purity ca.35% evaporation) The filter cake was extracted with several portions of boiling n-hexane. Each hot mixture was filtered through glass frit (G4), and the obtained filtrate was evaporated to dryness in order to weigh the residue (in the same receiving flask) to control the extraction efficiency. Sensitivity: Internal Hexane, ml weight, g 130 4.7 130 9.1 100 9.9 70 10.1 Then, the combined residue was stirred with 30 ml of n-pentane for 15 min at room temperature, and the formed suspension was filtered through glass frit (G3), and the filter cake was additionally washed with 2x10 ml of n-pentane and then dried under vacuum to give 9.5 g (11.38 mmol, 89.5%) of pure anti-MC3M (as a yellowish solid, solvate with ca.0.9 molecule of hexane). Example 5 In this Example, anti / syn-dimethylsilanediyl[2-methyl-4,8-di(3,5-dimethylphenyl)-1,5,6,7-tetrahydro- s-indacen-1-yl][2-ethyl-4-(3,5-dimethylphenyl)-5-methoxy-6-tert-butylinden-1-yl]zirconium dichloride (MC4) was prepared. This was converted into anti-dimethylsilanediyl[2-methyl-4,8-di(3,5- dimethylphenyl)-1,5,6,7-tetrahydro-s-indacen-1-yl][2-ethyl-4-(3,5-dimethylphenyl)-5-methoxy-6-tert- butylinden-1-yl] zirconium dimethyl (MC4M). Synthesis of the ligand: Ethylmalonic acid A solution of 196.4 g (3.5 mol) of potassium hydroxide in 1000 cm3of water was added to a solution of 188.2 g (1.0 mol) of diethyl ethylmalonate in 500 ml of methanol. The resulting mixture was refluxed for 5 h, then ethanol and methanol were distilled off. Then, 1000 cm3of water was added and the obtained mixture was acidified with 12 M HCl to pH 1.0. Ethylmalonic acid was extracted with 5 ^300 ml of ether. The combined extract was evaporated to dryness and the residue was dried under vacuum. This procedure gave 120.2 g (91.0%) of ethylmalonic acid as white solid.1H NMR (DMSO-d6): δ 4.28 (br.s, 2H), 3.12 (d, J = 7.4 Hz, 1H), 1.71 (quin, J = 7.40 Hz, 2H), 0.86 (t, J = 7.4 Hz, 3H).13C NMR (CDCl3): δ 171.12, 53.36, 22.01, 11.95. Sensitivity: Internal 2-Ethylacrylic acid g, was added dropwise at 5 °C to a solution of ethylmalonic acid (118.8 g, 899.2 mmol) in 1300 ml of ethyl acetate. Paraform (38.4 g, 1.28 mol) was added to the obtained suspension. The resulting mixture was refluxed for 5 h, then cooled to 5 °C, then 600 ml of ether and 1700 cm3of 2 M HCl were added. After mixing, the organic layer was separated, the aqueous layer was additionally extracted with 2 ^700 ml of ether. The combined organic extract was dried over Na2SO4 and then carefully evaporated to dryness. The residue was purified by vacuum distillation to give 2-ethylacrylic acid, bp 75-77oC / 6 mm Hg. Yield 79.8 g (88.6%, average of two experiments) of a colorless liquid. 1H NMR (CDCl3): δ 12.55 (br.s, 1H), 6.28 (m, 1H), 5.64 (m, 1H), 2.32 (qm, J = 7.5 Hz, 2H), 1.08 (t, J = 7.5 Hz, 3H). 6-tert-Butyl-5-methoxy-2-ethylindan-1-one g, was added to Eaton's reagent obtained from 103.5 g of P4O10 and 520 ml of MeSO3H at 50 °C. To this rapidly stirred mixture, 1-tert-butyl-2- methoxybenzene (61.7 g, 375.7 mmol) was added dropwise over ca.1 h at 50-53 °C (hot water bath). The resulting mixture was stirred for 1 h at this temperature, then cooled to room temperature, and poured on a mixture of 1.0 liter of cold water and 1 kg of ice. The crude product was extracted with 3 ^400 ml of dichloromethane. The combined organic extract was washed with aqueous K2CO3, dried over K2CO3, filtered through a short pad of silica gel 60 (40-63 µm) and then evaporated to dryness. The residue was purified by vacuum distillation to give 81.18 g (87.7 %, ca.90% purity) of 6-tert-butyl- 5-methoxy-2-ethylindan-1-one as a yellowish oil (bp 150-170oC / 5 mm Hg). 1H NMR (CDCl3): δ 7.65 (s, 1H), 6.85 (s, 1H), 3.90 (s, 3H), 3.20 (dd, J = 17.2 Hz, J = 7.7 Hz, 1H), 2.71 (dd, J = 17.2 Hz, J = 3.6 Hz, 1H), 2.59-2.51 (m, 1H), 1.99-1.87 (m, 1H), 1.54-1.41 (m, 1H), 1.35 (s, 9H), 0.97 (t, J = 7.4 Hz, 3H).13C NMR (CDCl3): δ 207.59, 164.52, 154.75, 138.65, 129.31, 121.87, 107.72, 55.15, 48.86, 35.00, 31.93, 29.54, 24.61, 11.56. Sensitivity: Internal 4-Bromo-6-tert-butyl-2-ethyl-5-methoxyindan-1-one Bromine (18.5 ml, 57.4 g, 359.1 mmol) was added dropwise over 5 min at 5 °C to a mixture of 6-tert- butyl-2-ethyl-5-methoxyindan-1-one (81.18 g, 329.5 mmol), 100.4 g of sodium acetate, 3.0 g of nBu4NI, 280 ml of dichloromethane, and 570 ml of water. This mixture was stirred for 2 h at 5 °C, then a solution of 46.3 g of sodium acetate in 260 ml of water was added followed by addition of 9.7 ml (30.1 g, 188.3 mmol) of bromine. The resulting mixture was additionally stirred for 1 h at this temperature and then washed by aqueous Na2SO3 to remove excess bromine. The crude product was extracted with 3 ^250 ml of dichloromethane. The combined organic extract was dried over K2CO3, evaporated to dryness, and the residue was dried in vacuum. This procedure gave 105.3 g (98.1%, ca.90% purity) of 4-bromo-6-tert-butyl-2-ethyl-5-methoxyindan-1-one as a yellowish oil which was used without further purification. 1H NMR (CDCl3): δ 7.69 (s, 1H), 4.03 (s, 3H), 3.21 (dd, J = 17.6 Hz, J = 7.8 Hz, 1H), 2.70 (dd, J = 17.6 Hz, J = 3.7 Hz, 1H), 2.66-2.58 (m, 1H), 2.03-1.91 (m, 1H), 1.60-1.47 (m, 1H), 1.40 (s, 9H), 1.03 (t, J = 7.4 Hz, 3H).13C NMR (CDCl3): δ 207.14, 162.57, 154.07, 145.20, 133.07, 121.13, 116.50, 61.45, 48.79, 35.46, 33.36, 30.45, 24.34, 11.43. 6-tert-Butyl-2-ethyl-5-methoxy-4-(3,5-dimethylphenyl)-indan-1-one A mixture of 64.08 g (197.0 mmol) of 4-bromo-6-tert-butyl-2-ethyl-5-methoxyindan-1-one, 37.32 g (248.8 mmol, 1.26 equiv.) of 3,5-dimethylphenylboronic acid, 1.02 g (2.0 mmol, 1 mol.%) of Pd(PtBu3)2, 63.4 g of Na2CO3, 325 ml of 2-methyltetrahydrofurane, and 290 ml of water was refluxed for 6 h. Then 500 ml of water was added, the organic layer was separated, and the aqueous layer was extracted with 200 ml of dichloromethane. The combined organic extract was dried over K2CO3and then evaporated to dryness to give slightly yellowish oil. The product was isolated by flash- chromatography on silica gel 60 (40-63 µm, eluent: hexanes-dichloromethane = 1:1 and then 1:5, vol.). Yield 62.95 g (91.2%, purity ca.95%) of a slightly yellowish oil. 1H NMR (CDCl3): δ 7.73 (s, 1H), 7.03 (s, 1H), 7.02 (s, 2H), 3.32 (s, 3H), 3.06 (dd, J = 18.3 Hz, J = 8.6 Hz, 1H), 2.57-2.47 (m, 2H), 2.39 (s, 6H), 2.00-1.87 (m, 1H), 1.54-1.40 (m, 1H), 1.42 (s, 9H), Sensitivity: Internal 0.95 (t, J = 7.4 Hz, 3H).13C NMR (CDCl3): δ 208.30, 163.42, 153.15, 143.21, 138.06, 136.27, 132.68, 131.42, 129.07, 127.17, 121.11, 60.47, 49.00, 35.33, 31.69, 30.49, 24.48, 21.36, 11.67. 5-tert-Butyl-2-ethyl-6-methoxy-7-(3,5-dimethylphenyl)-1H-indene NaBH4 (10.2 g, 269.6 mmol, 1.5 equiv.) was added to a solution of 62.95 g (179.6 mmol) of 6-tert- butyl-2-ethyl-5-methoxy-4-(3,5-dimethylphenyl)-indan-1-one in 300 ml of THF cooled to 5 °C. To this mixture 150 ml of MeOH was added dropwise over ca.5 h at 5 °C, and the resulting mixture was stirred overnight at room temperature. Then, this mixture was evaporated to dryness, 700 ml of dichloromethane and 700 ml water were added to the residue, and the so obtained mixture was acidified with 2 M HCl to pH~6.5. The organic layer was separated, the aqueous layer was additionally extracted with 100 ml of dichloromethane. The combined organic extract was passed through a pad (~30 ml) of silica gel 60 (40-63 µm; eluent: dichloromethane) to get rid of most of the palladium black. The obtained elute was evaporated to dryness to give a grey oil. This oil was dissolved in 300 ml of toluene and TsOH (0.3 g) was added to it. This mixture was refluxed with Dean-Stark head for 10 min and then cooled to room temperature using a water bath. The formed solution was washed with 10% Na2CO3, the organic layer was separated, the aqueous layer was extracted with 150 ml of dichloromethane. The combined organic extract was dried over K2CO3and then evaporated to dryness. The crude product was purified by flash chromatography on silica gel 60 (40-63 µm, hexanes-dichloromethane = 10:1) followed by vacuum distillation to give 53.14 g (88.5%) of 5-tert-butyl-2-ethyl-6-methoxy-7-(3,5-dimethylphenyl)-1H-indene as a yellowish oil (bp 175-195oC / 2 mm Hg). 1H NMR (CDCl3): δ 7.22 (s, 1H), 7.09 (s, 2H), 6.99 (s, 1H), 6.45 (t, J = 1.4 Hz, 1H), 3.25 (s, 3H), 3.13 (s, 2H), 2.41 (q, J = 7.4 Hz, 2H), 2.37 (s, 6H), 1.44 (s, 9H), 1.14 (d, J = 7.4 Hz, 3H).13C NMR (CDCl3): δ 154.25, 151.76, 141.51, 140.88, 140.43, 138.31, 137.66, 131.91, 128.46, 127.20, 124.97, 117.17, 60.66, 41.00, 35.13, 31.01, 24.25, 21.43, 13.47. [6-tert-Butyl-4-(3,5-dimethylphenyl)-2-ethyl-5-methoxy-1H-inden-1-yl] chlorodimethylsilane Sensitivity: InternalnBuLi in hexanes (2.5 M, 10.9 ml, 27.25 mmol) was added in one portion to a solution of of 5-tert- butyl-7-(3,5-dimethylphenyl)-2-ethyl-6-methoxy-1H-indene (9.05 g, 27.06 mmol) in 200 ml of ether cooled to –50 °C. This mixture was stirred overnight at room temperature, then the resulting orange- yellow solution was cooled to –50 °C, then dichlorodimethylsilane (16.3 ml, 17.44 g, 135.1 mmol, 5.0 equiv.) was added to it in one portion. The resulting mixture was stirred overnight at room temperature, then filtered through a glass frit (G3 mesh size), and the filter cake was washed with 2 ^50 ml of toluene. The combined filtrate was evaporated to dryness to give the title compound as a yellowish thick oil that was used without further purification. 1H NMR (CDCl3): δ 7.39 (s, 1H), 7.09 (s, 2H), 6.99 (s, 1H), 6.45 (s, 1H), 3.65 (s, 1H), 3.24 (s, 3H), 2.67-2.46 (m, 2H), 2.38 (s, 6H), 1.43 (s, 9H), 1.15 (t, J = 7.5 Hz, 3H), 0.43 (s, 3H), 0.15 (s, 3H).13C NMR (CDCl3): δ 155.83, 152.58, 143.55, 137.96, 137.58, 137.55, 136.53, 128.33, 127.90, 127.74, 124.52, 121.00, 60.46, 48.34, 35.16, 31.17, 24.71, 21.44, 13.76, 1.21, -0.66. [4,8-Bis(3,5-dimethylphenyl)-2-methyl-1,5,6,7-tetrahydro-s-indacen-1-yl][6-tert-butyl-4-(3,5- - To a cooled to -50oC suspension of 5.5 g (14.5 mmol) of 4,8-di(3,5-dimethylphenyl)-6-methyl-1,2,3,5- tetrahydro-s-indacene in a mixture of 60 ml of ether and 20 ml of THF 5.8 ml (14.5 mmol) of 2.5 M nBuLi in hexanes was added in one portion. The resulting mixture was stirred overnight at room temperature, then thus obtained light-orange solution with a large amount of orange precipitate was cooled to -50°C, and 110 mg of CuCN was added. The obtained mixture was stirred for 0.5 h at -25oC, then a solution of ca.14.5 mmol of [6-tert-butyl-4-(3,5-dimethylphenyl)-2-ethyl-5-methoxy-1H-inden- 1-yl](chloro)dimethylsilane in 100 ml of ether was added in one portion. This mixture was stirred overnight at room temperature, then filtered through a pad of silica gel 60 (40-63 um), which was additionally washed by 2x50 ml of ether. The combined organic elute was evaporated to dryness. The crude product was purified by flash chromatography on silica gel 60 (40-63 um, 600 ml, eluent: Sensitivity: Internal hexanes: dichloromethane = 5:1, vol.). The combined elute was evaporated to dryness, and the residue was dried in vacuum at elevated temperature to give 9.75 g (87.4%, purity ca.97%) of the title product (as a ca 59:41 mixture of the stereoisomers) as a slightly yellowish glassy solid. Anti-dimethylsilanediyl[2-methyl-4,8-di(3,5-dimethylphenyl)-1,5,6,7-tetrahydro-s-indacen-1-yl][2- ethyl-4-(3,5-dimethylphenyl)-5-methoxy-6-tert-butylinden-1-yl] zirconium dimethyl. nBuLi in hexanes (2.5 M, 10.1 ml, 25.2 mmol) was added in one portion at room temperature to a yellowish solution of 9.75 g (ca.12.67 mmol) of [4,8-bis(3,5-dimethylphenyl)-2-methyl-1,5,6,7- tetrahydro-s-indacen-1-yl][6-tert-butyl-4-(3,5-dimethylphenyl)-5-methoxy-2-ethyl-1H-inden-1- yl]dimethylsilane in 70 ml ofnBu2O. This mixture was stirred overnight at room temperature, then the resulting solution was cooled to 0 °C, and ZrCl4(2.95 g, 12.67 mmol) was added. The reaction mixture was stirred for 24 h at room temperature to give an orange-red suspension. This mixture was evaporated to dryness. On the evidence of NMR spectroscopy, the resulting solid included a ca.88:12 mixture of anti- and syn-zirconocene dichlorides. To this solid, 18.06 ml (30.35 mmol, 2.4 equiv.) of 1.68 M MeMgCl in THF were added, and the obtained mixture was stirred for 11.5 h at 90 °C. The resulting suspension was evaporated to dryness. The filter cake was extracted with several portions of boiling n-hexane (1x100 ml plus 3x50 ml). Each hot suspension was filtered through glass frit (G4), and the obtained filtrate was evaporated to dryness in order to weigh the residue (in the same receiving flask) to control the extraction efficiency. Then, the combined residue was stirred with 35 ml of n-pentane for 15 min at room temperature, and the formed suspension was filtered through glass frit (G3), the solid was dried under vacuum to give 9.4 g of a yellowish solid of pure anti-MC4M containing ca.0.16 mol of n-hexane per mol of Zr, so the adjusted net weight of the isolated complex was ca.9.25 g (82.2%). The mother liquor was evaporated to dryness to give one more crop (1.0 g, ca.80-95% purity) of anti-MC4M. Anal. calc. for C . 57H68OSiZr*0.16C6H14: C, 77.09; H, 7.78. Found: C 77.21; H, 7.70.1H NMR (CDCl3): δ 7.36 (s, 1H), 7.18 (s, 2H), 7.14 (s, 2H), Sensitivity: Internal 7.06 (s, 1H), 6.98 (s, 2H), 6.95 (s, 1H), 6.94 (s, 1H), 6.77 (s, 1H), 6.64 (s, 1H), 3.28 (s, 3H), 3.12- 2.94 (m, 2H), 2.90-2.83 (m, 1H), 2.44-2.31 (m, 20H), 2.17 (s, 3H), 2.04-1.93 (m, 2H), 1.79-1.72 (m, 1H), 1.33 (s, 9H), 0.95 (s, 3H), 0.90 (t, J = 7.5 Hz, 3H), -0.35 (s, 3H), -0.96 (s, 3H), -1.19 (s, 3H).13C NMR (CDCl3): δ 157.44, 142.30, 141.89, 141.62, 140.58, 140.24, 139.29, 137.95, 137.75, 137.65, 137.38, 137.00, 134.56, 132.57, 131.90, 130.37, 130.24, 129.03, 128.60, 128.30, 127.85, 127.37 (br. s), 126.88, 126.75, 123.57, 121.85, 116.55, 112.93, 77.77, 62.05, 35.58, 34.66, 33.86, 32.48, 30.65, 26.20, 25.13, 21.48, 21.44, 21.22, 19.59, 16.89, 4.08, 2.32. Example 6 In a separate experiment, 10.7 g (ca.11 mmol) of crude (that is, still containing LiCl and other by- products from the transmetalation reaction from the ligand lithium salt and ZrCl4) MC4 complex was obtained with anti / syn = 87:13. Epimerization was carried out in vials at two temperatures: 70 °C and 90 °C; the reaction was monitored by1H NMR at 2 h time intervals.2 h. For every checkpoint, 1 mmol of the complex (0.97 g) and 1.42 ml of 1.68 M MeMgCl were taken. The results are shown in the following table: 2h 4h 6h 8h 10h 90 / 10 + 70 °C - impurities 98 / 2 99 / 1 88 / 12 + 91 / 9 + 90 °C impurities impurities 99 / 1 This experiment shows that epimerisation is faster at higher temperature, but is still feasible and almost quantitative also at 70 °C. The following examples confirm that epimerisation is faster on the dimethyl compared to the dichloride, that the basic ligand skeleton of Formula I is required for efficient epimerisation, and that MeMgCl is a more efficient epimerisation agent than MgCl2 or LiCl. Comparative Example 7: epimerization with LiCl-THF LiCl (300 mg, 7.08 mmol) and THF (20 ml) were added to anti / syn-MC180:20 (1.80 g, 1.97 mmol) at room temperature) and the obtained mixture was stirred for 20 h at 65 °C. Then the reaction temperature was raised to 80 °C and stirring was continued at this temperature. The progress of epimerization was monitored by1H NMR spectroscopy, and the results are shown in Table 2: Table 2 Sensitivity: Internal Time, h Temperature, Anti / syn ratio Organometalli °C c impurities, % 0 (initial ca.80:20 8 ratio) 20 65 ca.87:13 0 40 80 ca.90:10 0 60 80 ca.92:8 0 80 80 ca.95:5 0 Therefore, the yield and purity of the anti isomer obtainable with this process (synthesis followed by epimerisation with LiCl in THF) needs at least 60 hours at 80 °C to reach anti / syn =95:5 starting from an 87:13 anti / syn mixture. Comparative Example 8 THF (5 ml) was added to a mixture of 0.75 g (0.819 mmol) of MC1 (anti / syn ~85 / 15) and 70 mg (1.65 mmol, 2.01 equiv.) of LiCl, and the obtained homogeneous mixture was stirred at 70 °C. The progress of epimerization was monitored by1H-NMR spectroscopy (for the results, see table below). Reaction conditions: Reaction Time: Reaction Time: 2 equiv LiCl in THF at 70°C 19 h 59 h Initial MC1 anti / syn = 85 / 15 anti / syn = 87 / 13 anti / syn = 91 / 9 This experiment confirms that the anti / syn ratio reachable with LiCl / THF is still relatively low, and the time may be too long for an economically meaningful industrial production. Comparison Example 9: epimerization with anhydrous MgCl2in THF Me3SiCl (7.4 ml, 6.32 g, 58.2 mmol, 1.15 equiv.) was added to MeMgCl in THF (1.68 M, 30.0 ml, 50.4 mmol) previously cooled to 0°C. The obtained mixture was triturated with spatula, then diluted with ca.200 ml of n-hexane, stirred for 15 min at room temperature, and the formed precipitate was filtered off (G3 mesh size). This precipitate was washed with 2 ^10 ml of n-hexane and dried in vacuum for 2 h at room temperature. This procedure gave 11.8 g of MgCl2(THF)3. THF (2 mL) and MgCl2(THF)3(39 mg, 0.124 mmol) were added to anti / syn-MC183:17 (750 mg) and the obtained mixture was stirred at 90 °C. The progress of epimerization was monitored by1H- NMR spectroscopy (for the results, see table below). Sensitivity: Internal Reaction Time / h 2 7 24 48 Anti / Syn Ratio 83 / 17 85 / 15 87 / 13 90 / 10 This experiment confirms that the anti / syn ratio reachable with MgCl2 / THF is still relatively low, and the reaction time may be too long for an economically meaningful industrial production. TEBAC (10.0 g, 43.9 mmol) andnBu2O (170 ml) were added to 27.5 g of a mixture of syn- and anti- MC1 (anti / syn-ratio ~ 85:15). The obtained mixture was stirred at 120 °C for 70 h. Then this mixture was evaporated to dryness, the residue was taken up with 150 ml of toluene and the suspension was heated to 80 °C for 20 min and then filtered through glass frit (G4). On the evidence of1H NMR spectroscopy, the resulting filtrate contains a mixture of anti- and syn-zirconocene dichlorides in the ratio anti / syn=97:3, contaminated with about 10% impurities. This experiment uses a different epimerization reagent and reaches a higher anti / syn ratio, but substantial decomposition is observed, and again the time needed to reach this 97:3 ratio (about three days) may be too long for an economically meaningful industrial production. Comparison example 11: Epimerisation of a mixture of anti- and syn-MC1 in CH2Cl2 with TEBAC TEBAC (benzyltriethylammonium chloride, 24 mg, 0.105 mmol, 20 mol.%) and 2 ml of CH2Cl2 were added to 0.48 g (0.52 mmol) of a ca.85:15 mixture of anti- and syn-MC1. The obtained reddish homogeneous mixture was stirred at room temperature for 96 h. Afterwards, additional 24 mg (0.105 mmol, 20 mol.%, i.e.40 mol.% in total) of TEBAC was added, and the reaction mixture was stirred for additional 48 h. The progress in isomerization was monitored by1H NMR spectroscopy (for the results, see table below). Time, h anti / syn ratio 0 ca.85 / 15 24 ca.89 / 11 96 ca.91 / 9 144* ca.95 / 5 *Additional TEBAC was added after 96 h Sensitivity: Internal This experiment expands the solvent type to include low boiling chlorinated solvents, and shows that a high temperature is not required, but the yield and purity of the anti isomer obtainable with this process is still relatively low, and the time needed to reach this 95:5 ratio (more than 6 days) may be too long for an economically meaningful industrial production. Examples 12a, 12b, and 12c: One-pot methylation / epimerisation of the 85:15 mixture of anti / syn-MC1 by MeLi in THF (that is, epimerisation without LiCl) MeLi in diethyl ether (1.6 M, 4.44 ml, 7.1 mmol, 2.0 equiv.) was added to a solution of MC1 (anti / syn=85 / 15, 3.25 g, 3.55 mmol) in 20 ml of THF at room temperature. The obtained homogeneous mixture was stirred for 1 h at this temperature. Then, diethyl ether and a part of THF were distilled off under vacuum, and the resulting solution was divided into 4 equal portions. Additional THF was added to three of these portions to bring the total volume of each to ca.5 ml, and the resulting mixtures were stirred at 70°C (Example 12a), 80°C (Example 12b) and 90°C (Example 12c). The progress of epimerization was monitored by1H-NMR spectroscopy (for the results, see table below). Reaction Reaction time MC1M Example conditions (hours) anti / syn ratio 0 85:15 2 equiv MeLi in Example 12a 19 90:10 THF at 70°C 59 94:6 0 85:15 2 equiv MeLi in Example 12b 19 91:9 THF at 80°C 59 95:5 0 85:15 2 equiv MeLi in Example 12c 19 91:9 THF at 90°C 59 96:4 0 85:15 2 equiv LiCl in Comparative example 8 19 87:13 THF at 70°C 59 91:9 Sensitivity: Internal 13: C2- metallocene MC5M and after one- pot methylation-epimerisation with MeMgCl in THF at 90 °C, pure rac-MC5M has been obtained in 45 % yield. The rate of conversion is shown in the table below. Figure 1 plots the epimerisation rate of MC1M compared to that of MC5M. The plot shows that epimerisation of MC1 is faster. Epimerisation rate of MC5M 2 in THF Time, h rac / meso 0 67:33 3 70:30 24 75:25 Sensitivity: Internal

Claims

Claims 1. A method of producing a metallocene complex, said method comprising reacting a C1- symmetric, bridged bisindenyl metallocene in its syn-configuration with an organometallic reagent selected from an organolithium of the formula R”Li and a Grignard reagent of the formula RMg-X’, wherein R and R” are each independently C1to C6alkyl or benzyl, and X’ is halogen, wherein the C1-symmetric, bridged bisindenyl metallocene in its syn- configuration has the Formula (1):wherein: Mt is Zr or Hf; X is halogen or an -OY group or an -NY2group, wherein Y is a C1to C20hydrocarbyl group, optionally containing up to two heteroatoms from Group 14-16 of the Periodic Table; each Ar is independently selected from aryl and heteroaryl containing up to two heteroatoms from Group 15-16 of the Periodic Table; each aryl and / or heteroaryl being optionally substituted with a substituent selected from halogen and C1- C20hydrocarbyl, said C1- C20hydrocarbyl optionally containing up to two heteroatoms from Group 14-16 of the Periodic Table; each R1is independently selected from H; C1 to C20 hydrocarbyl, optionally containing up to two heteroatoms from Group 14-16 of the Periodic Table; or, together with the Si atom to which the R1atoms are attached, form a C4 to C8 ring; Sensitivity: InternalR2and R2’are, independently from each other, C1to C20hydrocarbyl, optionally containing up to two heteroatoms from Group 14-16 of the Periodic Table; R5and R6are, independently from each other, H or C1to C20hydrocarbyl, optionally containing up to two heteroatoms from Group 14-16 of the Periodic Table; or, together with the C atoms to which they are attached, R5and R6form a C4to C7ring; R5’is H or C1to C20hydrocarbyl group, optionally containing up to two heteroatoms from Group 14-16 of the Periodic Table; or a -OY group; and R6’is a tertiary hydrocarbyl of the formula -CRx3, with Rxbeing a linear or branched C1to C6alkyl group, C3to C8cycloalkyl group or C6to C10aryl group.

2. A method as claimed in claim 1, wherein the C1-symmetric, bridged bisindenyl metallocene in its syn-configuration is of the Formula (2)wherein: Mt is Zr or Hf; X is halogen or an -OY group or an -NY2group, wherein Y is a C1to C20hydrocarbyl group, optionally containing up to two heteroatoms from Group 14-16 of the Periodic Table; each R1is independently selected from H; C1to C20hydrocarbyl, optionally containing up to two heteroatoms from Group 14-16 of the Periodic Table; or, together with the Si atom to which the R1atoms are attached, form a C4 to C8 ring; R2and R2’are, independently from each other, of the formula -CHRy2 or -CH2Ry, with Rybeing H, a linear or branched C1 to C6 alkyl group, C3 to C8 cycloalkyl group or C6 to C10 aryl group; Sensitivity: InternalR3and R4are, independently from each other, H; C1to C20hydrocarbyl, optionally containing up to two heteroatoms from Group 14-16 of the Periodic Table or wherein two adjacent R3or R4groups, together with the carbon atoms of the phenyl to which they are bound, form part of a C4to C7ring; R5and R6are, independently from each other, H or C1to C20hydrocarbyl, optionally containing up to two heteroatoms from Group 14-16 of the Periodic Table; or, together with the C atoms to which they are attached, R5and R6form a C4to C7ring; R5’is H or C1to C20hydrocarbyl group, optionally containing up to two heteroatoms from Group 14-16 of the Periodic Table; or a -OY group; and R6’is a tertiary hydrocarbyl of the formula -CRx3, with Rxbeing a linear or branched C1to C6alkyl group C3to C8cycloalkyl group or C6to C10aryl group.

3. A method as claimed in claim 1 or 2, wherein R6’is of the formula -C(CH3)3and / or R5’ is OY, where Y is a C1to C6hydrocarbyl, optionally containing up to two silicon atoms.

4. A method as claimed in any one of the preceding claims, wherein X is halogen, preferably Cl.

5. A method as claimed in any one of the preceding claims, wherein the C1-symmetric, bridged bisindenyl metallocene in its syn-configuration is reacted with a Grignard reagent of the formula RMg-X’, wherein X’ is halogen, and R is C1 to C6 alkyl or benzyl; preferably C1 to C5, C1 to C4 alkyl or C1 to C3 alkyl, or benzyl; more preferably methyl, ethyl or benzyl; most preferably methyl or benzyl.

6. A method as claimed in claim 5, wherein X’ is Cl and R is methyl or benzyl, preferably methyl.

7. A method as claimed in any one of claims 1 to 4, wherein the C1-symmetric, bridged bisindenyl metallocene in its syn-configuration is reacted with an organolithium of the formula R”Li, wherein R” is C1 to C6 alkyl or benzyl; preferably C1 to C5, C1 to C4 alkyl or C1 to C3 alkyl, or benzyl; more preferably methyl, ethyl or benzyl; most preferably methyl.

8. A method as claimed in any one of the preceding claims, wherein a mixture of the syn- and anti- isomers of the C1-symmetric, bridged bisindenyl metallocene is reacted with the organometallic reagent, and, wherein, preferably, said mixture has an anti-syn ratio of ≥ 65:

35. Sensitivity: Internal9. A method as claimed in claim 8, wherein the reaction produces a mixture of syn- and anti- isomers of a C1symmetric bridged bisindenyl di(C1-6alkyl) metallocene or C1symmetric bridged bisindenyl di(benzyl) metallocene that has an anti-syn ratio that is greater, preferably, at least 10% greater, than the anti-syn ratio of the mixture of syn- and anti- isomers of the C1-symmetric, bridged bisindenyl metallocene that is reacted with the organometallic reagent.

10. A method as claimed in any one of the preceding claims, wherein the reaction produces a mixture of syn- and anti- isomers of a C1symmetric bridged bisindenyl di(C1-6alkyl) metallocene or C1symmetric bridged bisindenyl di(benzyl) metallocene having an anti- syn ratio that is ≥ 90:

10.

11. A method as claimed in any one of the preceding claims, wherein the organometallic reagent is reacted with the C1-symmetric, bridged bisindenyl metallocene in a greater than stoichiometric amount.

12. A method as claimed in any one of the preceding claims, wherein the reaction produces a C1 symmetric bridged bisindenyl di(C1-6 alkyl) metallocene or a C1 symmetric bridged bisindenyl di(benzyl) metallocene, and the method further comprises recovering the bridged bisindenyl di(C1-6 alkyl) metallocene or bridged bisindenyl di(benzyl) metallocene produced.

13. A method as claimed in claim 12, wherein the C1symmetric bridged bisindenyl di(C1-6alkyl) metallocene or C1symmetric bridged bisindenyl di(benzyl) metallocene produced is recovered in the anti- configuration by solvent extraction.

14. A method as claimed in claim 13, wherein solvent extraction is carried out in pentane, hexane and / or toluene.

15. A method for polymerising propylene, which comprises polymerising propylene and optionally at least one comonomer selected from ethylene and C4 to C10 alpha olefin comonomers with a catalyst comprising the recovered bridged bisindenyl di(C1-6 alkyl) metallocene or bridged bisindenyl di(benzyl) metallocene from any one of claims 12 to Sensitivity: Internal

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