Metathesis compositions comprising air-stable imido alkylidene complexes

Abstract

The invention relates to a composition comprising a Schrock-alkylidene complex bearing a neutral ligand selected from 1,10-phenanthroline and 2,2'-bipyridine, and a one or more compound(s) comprising an olefinic double bond, respectively. When the complexes are non-dissociative, they can be thermoactivated to initiate a metathesis reaction in the composition. The invention further relates to a composition comprising a Schrock-alkylidene complex bearing a neutral 2,2'-bipyridine ligand, and one or more compound(s) comprising an olefinic double bond, respectively, wherein the complex is autoactivating.

Description

Verbio Vereinigte BioEnergie AG 119468P771PC MR / ABB METATHESIS COMPOSITIONS COMPRISING AIR-STABLE IMIDO ALKYLIDENE COMPLEXES FIELD OF THE INVENTION

[0001] The invention relates to a composition capable of performing a metathesis reaction, the composition comprising a 18-electron molybdenum or tungsten alkylidene complex formed by a 14-electron molybdenum or tungsten alkylidene complex and a 1,10-phenanthroline or a 2,2’-bipyridine as a neutral bidentate ligand and one or more compounds comprising each an olefinic double bond. The complexes comprised in the compositions may be activated by heat to initiate a metathesis reaction. The invention further relates to a method of making the composition, and to a method of activating the composition. BACKGROUND OF THE INVENTION

[0002] Olefin metathesis reactions catalyzed by transition metal catalysts such as molybdenum or tungsten alkylidene catalysts - so-called Schrock catalysts - are among the most important reactions of organic synthetic chemistry. A valuable type of known catalysts is the group of Mo(VI) and W(VI) alkylidene complexes. The efficacy thereof depends on the type of metal, alkylidene group and ligands. While such catalysts have proved effective, they frequently lack stability in air which makes them more difficult to handle and often restricts their usefulness.

[0003] For improving air-stability, WO 2012 / 116695 (Fürstner) suggests stabilizing such catalysts by complexing them with bidentate heterocycles such as 1,10- phenanthroline and 2,2’-bipryridine. Exemplified 1,10-phenanthroline complexes are e.g. complexes 5 to 8wherein R24= methyl, phenyl; R25, R26= H, methyl, CF3; Z =methyl, iso-propyl, halogen.

[0004] However, such an air-stable product is not active catalytically, but the active form of the catalyst was known to be released by exposure to a Lewis acid such as MgCl2, MgBr2, MgI2, MnCl2, MnBr2, MnI2, FeCl3, AlCl3, CuCl2, ZnCl2, ZnBr2, ZnI2, Zn(triflate)2or Zn(trifluoroacetate)2. Presence of Lewis acids and the formation of adducts of phenanthroline with the Lewis acid generally results in a complex work-up of the reaction mixture to isolate the products of the reaction.

[0005] EP 3268377 B1 (XiMo AG) discloses tungsten imido alkylidene catalysts stabilized with 1,10-phenanthroline. The catalysts must be activated by addition of a Lewis acid such as zinc chloride. The activation is performed in an inert solvent such as toluene. Exemplified complexes are complexes III to VI:

[0006] The scientific publication from J. Heppekausen and A. Fürstner, “Rendering Schrock-type Molybdenum Alkylidene Complexes Air Stable: User-friendly Precatalysts for Alkene Metathesis”, Angew. Chem. Int. Ed. 2011, 50, 7829-7832, https: / / doi.org / 10.1002 / anie.201102012, discloses phenanthroline and bipyridine complexes 2, 3, 5, and 7 of Schrock catalysts which give no indications for partialdissociation (to 1, 4, or 6) in a solvent at room temperature as determined by NMR spectroscopy:Ar=2,6-diisopropylphenyl.

[0007] The authors state that complexes 2, 3, 5, and 7 are devoid of catalytic activity even at higher temperatures.

[0008] GB 2537416 discloses in Examples 3 and 6 metathesis catalysts complexed with 2,2’-bipyridine and a substituted bipyridinewhich may be activated by dissolution in an aprotic solvent such as deuterobenzene without the need for the addition of a Lewis acid because they spontaneously dissociate (see Examples 10 and 11 of GB 2537416). The inventors of GB 2537416 term the spontaneous liberation of the active catalyst in a solvent as an “autoactivating catalyst”.

[0009] This reference further discloses the homo-metathesis reaction of allylbenzene at room temperature catalyzed by. without using a solvent. The complex is autoactivating at room temperature, i.e., the complex dissociates into the 14-electron system and bipyridine. The conversion after 16 h was 54.2 %.

[0010] The concept of autoactivating bipyridine adducts has also been published in the scientific literature (Gulyás, H. et al. “Air-stable 18-electron adducts of Schrock catalysts with tuned stability constants for spontaneous release of the active species”, Commun. Chem. 4, 71 (2021); https: / doi.org / 10.1038 / s42004-021-00503-4). This reference discloses the homo-metathesis of methyl oleate in benzene at a temperature of 80 °C, and the ring-closing metathesis of diethyl diallyl malonate in benzene at room temperature using as catalyst the compound.

[0011] This reference further discloses the ring-opening metathesis polymerization of norbornene in toluene at 25 °C using as catalyst the compound.

[0012] WO 2021 / 239891 (Verbio) discloses Schrock-alkylidene complexes comprising a phenanthrene ligand D of the following formula as defined therein:.

[0013] The inventors of WO 2021 / 239891 discovered that Schrock-alkylidene complexes of the above formula having a stability constant in the range of from 5 L*mol-1to 250,000 L*mol-1when measured at 298 K and when the complex is dissolved in a solvent, are air-stable and catalytically active in an olefinic metathesis reaction without the necessity of removing the bidentate ligand by means of a Lewis acid, and hence unnecessarily forming the corresponding by-products, i.e., such complexes are autoactivating. Thus, this finite stability constant K serves in a selected solvent for an equilibrium between the 18-electron complex comprising the bidentate ligand andwhich is not active in an olefinic metathesis reaction, and the 14-electron complex from which the bidentate ligand has been released by dissociation, wherein the 14-electron complex is catalytically active in an olefinic metathesis reaction.

[0014] This reference specifically discloses in Example 7 the ethenolysis of a FAME (fatty acid methyl ester) in benzene at 50 °C using as catalyst the compound[O-TBS = O-Si(t-butyl)(Me)2].

[0015] The above complex is autoactivating. Its finite stability constant depends on the nature of the solvent. E.g., at room temperature (298 K), under similar conditions, it dissociates considerably more readily in CD2Cl2 than in C6D6. In CDCl3, the dissociation is even more favored. OBJECTS OF THE INVENTION

[0016] There is an ongoing need in the industry for providing compositions capable of performing an olefin metathesis reaction, wherein the complexes used in said compositions to initiate the reaction have improved air stability and allow a simplified handling in processing without a chemical activation and without the risk of a premature and uncontrollable reaction due to the high activity of the 14-electron complex (parent complex) or due to the dissociation (autoactivation) of the 18-electron adduct, when the complex or adduct and the substrate to be metathesized are mixed at room temperature.SUMMARY OF THE INVENTION

[0017] This object has been achieved with a composition defined in claim 1, namely with a composition capable of performing a metathesis reaction, the composition comprising: (X) a 14-electron Schrock alkylidene compound complexed with a bidentate ligand selected from (a) a 1,10-phenanthroline (optionally substituted) and (b) a 2,2’-bipyridine (optionally substituted); to form a 18-electron alkylidene compound; and (Y) one or more compounds each comprising an olefinic double bond; wherein the composition (c) does not contain a Lewis acid selected from one or more of MgCl2, MgBr2, MgI2, MnCl2, MnBr2, MnI2, FeCl3, AlCl3, CuCl2, ZnCl2, ZnBr2, ZnI2, Zn(triflate)2 or Zn(trifluoroacetate)2; and (d) is at a temperature above 50 °C.

[0018] In a preferred embodiment, the composition (e) does not contain an inert solvent for the compound (X) and / or (Y).

[0019] The absence of (e) an inert solvent for the compound (X) and / or (Y) may be beneficially for compositions resulting in a metathesis product having a high melting point and from which a solvent to be removed would require additional processing.

[0020] The inventors discovered that the 18-electron alkylidene compound (X) may be tuned such to remain non-dissociative at least up to room temperature in a composition comprising the 18-electron alkylidene compound (X) and the one or more compounds (Y) each comprising an olefinic double bond to be metathesized. Thisallows for a proper mixing and ample process time without any premature reaction even if the composition does not contain an inert solvent for the compound (X) and / or (Y). This is of relevance when reactions are carried out at an industrial scale since such reactions must be controllable.

[0021] The inventors of the present invention have further discovered that even when no dissociation of the 18-electron alkylidene compound into the 14-electron Schrock alkylidene compound and the bidentate compound at least up to room temperature may be observed by1H NMR analysis, a metathesis reaction can be initiated at higher temperature without the need for a chemical activation. The inventors of the present invention term this effect as thermoactivating. This could not be expected in view of the hitherto assumption that only the compound being devoid of the neutral bidentate ligand is active (see J. Heppekausen and A. Fürstner as referred to in the Background section).

[0022] The term “non-dissociative complex” as used herein means that the complexes are thermodynamically stable at least up to room temperature. Thermodynamically stable means that the complex (adduct) dissolved or dispersed in a solvent or the substrate does not dissociate significantly enough to be observed by1H NMR spectroscopy.

[0023] This is in stark contrast to the autoactivating (dissociative) complexes as discussed in the Background section which clearly appear to be thermodynamically unstable since their dissociation can be readily detected by1H NMR spectroscopy.

[0024] In a preferred embodiment, the compound (X) has a stability constant which exceeds a value of 250,000 L*mol-1at 298 K in a solvent, wherein the solvent is the one or more compounds (Y) each comprising an olefinic double bond, and / or wherein the solvent is an inert solvent for the compound (X) and / or (Y), the stability constant being determined as defined herein. BRIEF DESCRIPTION OF THE FIGURES

[0025] In the figures showsFig.1 Applicant’s1H NMR spectrum of complex, the complex being known from Heppekausen and Fürstner as referred to in the Background section, at room temperature (C6D5CD3, 298 K, 0.01 M); Fig.2 the1H NMR spectrum of said compound at 70 °C; Fig.3 the1H NMR spectrum of said compound at 95 °C; Fig.4 the1H NMR spectrum of said compound after cooling the 95 °C sample to room temperature; Fig.5 the temperature dependency of the stability constant of Mo(NArdiiPr)(CHCMe2Ph)(OC(CF3)2Me)2(2,2’-bipyridine). DETAILED DESCRIPTION OF THE INVENTION

[0026] Compositions according to the invention

[0027] The invention relates to a composition capable of performing a metathesis reaction, the composition comprising: (X) a 14-electron Schrock alkylidene compound complexed with a bidentate ligand selected from (a) a 1,10-phenanthroline (optionally substituted) and (b) a 2,2’-bipyridine (optionally substituted); to form a 18-electron alkylidene complex; and(Y) one or more compounds each comprising an olefinic double bond; wherein the composition (c) does not contain a Lewis acid selected from one or more of MgCl2, MgBr2, MgI2, MnCl2, MnBr2, MnI2, FeCl3, AlCl3, CuCl2, ZnCl2, ZnBr2, ZnI2, Zn(triflate)2 or Zn(trifluoroacetate)2; and (d) is at a temperature above 50 °C.

[0028] In a preferred embodiment, the composition does not contain (e) an inert solvent for the compound (X) and / or (Y).

[0029] In one embodiment, the invention relates to a composition, comprising: (X1) a compound of formula II (Y) one or more compounds each comprising an olefinic double bond; wherein M is Mo or W; A is selected from N-R1or O, wherein R1is C1-10alkyl or aryl, optionally respectively substituted; B is selected from pyrrole, indole and pyrazole, optionally respectively substituted; and C is selected from O-R2, wherein R2is C1-10alkyl or aryl, or (C1-10alkyl)3Si or (aryl)3Si, optionally respectively substituted; orB is identical to C, wherein C is selected from O-R2, wherein R2is C1-10alkyl or aryl, or (C1-10alkyl)3Si or (aryl)3Si, optionally respectively substituted; or B is different from C, wherein both B and C are selected from O-R2, wherein R2is C1- 10 alkyl or aryl, or (C1-10alkyl)3Si or (aryl)3Si, optionally respectively substituted; (a) D is 1,10-phenanthroline or substituted 1,10-phenanthroline; R3and R4are independently H, C1-10 alkyl or aryl, C1-10 alkyl and aryl being optionally substituted; and wherein only one of R3and R4is hydrogen; wherein the composition (c) does not contain a Lewis acid selected from one or more of MgCl2, MgBr2, MgI2, MnCl2, MnBr2, MnI2, FeCl3, AlCl3, CuCl2, ZnCl2, ZnBr2, ZnI2, Zn(triflate)2 or Zn(trifluoroacetate)2; and (d) is at a temperature above 50 °C.

[0030] In a preferred embodiment, the composition (e) does not contain an inert solvent for the compound (X) and / or (Y).

[0031] In a further embodiment, the invention relates to a composition, comprising (X2) a compound of formula II(Y) one or more compounds each comprising an olefinic double bond; whereinM is Mo or W; A is selected from N-R1or O, wherein R1is C1-10alkyl or aryl, optionally respectively substituted; B is selected from pyrrole, indole and pyrazole, optionally respectively substituted; and C is selected from O-R2, wherein R2is C1-10alkyl or aryl, or (C1-10alkyl)3Si or (aryl)3Si, optionally respectively substituted; or B is identical to C, wherein C is selected from O-R2, wherein R2is C1-10 alkyl or aryl, or (C1-10alkyl)3Si or (aryl)3Si, optionally respectively substituted; or B is different from C, wherein both B and C are selected from O-R2, wherein R2is C1-10 alkyl or aryl, or (C1-10alkyl)3Si or (aryl)3Si, optionally respectively substituted; (b) D is 2,2’-bipyridine or substituted 2,2’-bipyridine; R3and R4are independently H, C1-10alkyl or aryl, C1-10alkyl and aryl being optionally substituted; and wherein only one of R3and R4is hydrogen; wherein the composition (c) does not contain a Lewis acid selected from one or more of MgCl2, MgBr2, MgI2, MnCl2, MnBr2, MnI2, FeCl3, AlCl3, CuCl2, ZnCl2, ZnBr2, ZnI2, Zn(triflate)2 or Zn(trifluoroacetate)2; and (d) is at a temperature above 50 °C.

[0032] In a preferred embodiment, the composition (e) does not contain an inert solvent for the compound (X) and / or (Y).

[0033] According to the invention, M is Mo or W.

[0034] In one embodiment, M is W.

[0035] In another embodiment, M is Mo.

[0036] According to the invention, A is selected from N-R1or O, wherein R1is alkyl, preferably C1-10alkyl, or aryl, optionally respectively substituted.

[0037] In a preferred embodiment, A is N-R1, wherein R1is C1-10 alkyl or aryl, optionally respectively substituted.

[0038] The term “alkyl or C1-10alkyl” as used herein, e.g., used for the definition of R1, encompasses straight, branched, cyclic and alicyclic alkyl. A preferred C1-10 alkyl is C1- 5 alkyl. In another embodiment, C4-10 alkyl is preferred.

[0039] In one embodiment, alkyl such as R1is t-butyl or 1-adamantyl.

[0040] The term “aryl” as used herein, e.g., used for the definition of R1, encompasses phenyl, naphthyl, anthracenyl, and phenanthryl, optionally respectively substituted.

[0041] Suitable substituents may be selected from one or more of C1-10alkyl, C1-10alkoxy, phenyl, halogen, CN, and CF3.

[0042] Phenyl as aryl is preferred.

[0043] In one embodiment, R1is C1-10 alkyl or phenyl, respectively independently substituted with one or more of C1-10alkyl, C1-10alkoxy, phenyl, halogen, CN, and CF3.

[0044] According to the invention, in one embodiment, B is selected from pyrrole, indole and pyrazole, optionally respectively substituted.

[0045] In one embodiment, B is selected from pyrrole, indol and pyrazole, respectively independently substituted with one or more of C1-5 alkyl, C1-5 alkoxy or phenyl.

[0046] According to the invention, C is selected from O-R2, wherein R2is C1-10 alkyl or aryl, or (C1-10alkyl)3Si or (aryl)3Si, optionally respectively substituted.

[0047] In a preferred embodiment, R2is an electron-withdrawing group. The term “electron-withdrawing group” has a well-accepted meaning in the art.

[0048] In one embodiment, R2is phenyl substituted with -(CH2)4- to form an annulated ring with phenyl, or with -(CH=CH-CH=CH)- to form an annulated ring with phenyl. Herein, the annulated ring may be substituted with O-silyl.

[0049] The term “silyl” may be any silyl group forming a covalent bond between silicon and oxygen. Suitable silyl groups are e.g. t-butyldimethylsilyl (TBS, TBDMS), trimethylsilyl (TMS), triethylsilyl (TES), triisopropylsilyl (TIPS), t-butyldiphenylsilyl (TBDPS), and triphenylsilyl.

[0050] Likewise, the terms (C1-10alkyl)3Si or (aryl)3Si encompass the above-defined silyl groups.

[0051] According to the invention, D is a neutral bidentate ligand.

[0052] In the compound (X1) of formula I, said neutral ligand is (a) 1,10- phenanthroline or substituted 1,10-phenanthroline. Both N atoms of the phenanthroline scaffold bind to M, thus forming the bidentate ligand, and thus the 18-electron alkylidene compound.

[0053] In one embodiment, phenanthroline is substituted. In a preferred embodiment, phenanthroline is substituted with one or more electron-donating groups. The term “electron-donating group” has a well-accepted meaning in the art.

[0054] In one embodiment, 1,10-phenanthroline is independently substituted with one or more of C1-5 alkyl, C1-5 alkoxy, -O-(CH2)n-O- (n = 1 or 2), and phenyl. These groups represent electron-donating groups in the meaning of the invention.

[0055] Commercially available substituted 1,10-phenanthrolines comprising electron- donating substituents are 4,7-dimethyl-1,10-phenanthroline, 4,7-diphenyl-1,10- phenanthroline, 4,7-dimethoxy-1,10-phenanthroline, 3,8-dimethyl-1,10- phenanthroline, 3,8-dimethoxy-1,10-phenanthroline, 2,9-dimethyl-1,10- phenanthroline, 2,9-dimethoxy-1,10-phenanthroline, 5,6-dimethyl-1,10- phenanthroline, 5,6-diphenyl-1,10-phenanthroline, 5,6-dimethoxy-1,10- phenanthroline, and 1,10-phenanthroline[5,6-d]-1,3-dioxole.

[0056] In a further preferred embodiment, C is an electron-withdrawing group, and 1,10-phenanthroline is unsubstituted.

[0057] In a further preferred embodiment, C is an electron-withdrawing group, and 1,10-phenanthroline is substituted with one or more electron-donating groups as defined above.

[0058] In a further preferred embodiment, B is identical to C, wherein C is an electron- withdrawing group, and 1,10-phenanthroline is unsubstituted.

[0059] In a further preferred embodiment, B is identical to C, wherein C is an electron- withdrawing group, and 1,10-phenanthroline is substituted with one or more electron- donating groups as defined above.

[0060] In a further preferred embodiment, B is different from C, but both B and C are electron-withdrawing groups, and D is 1,10-phenanthroline or 1,10-phenanthroline substituted with one or more electron-donating groups as defined above.

[0061] In one embodiment, B is selected from pyrrole, indole and pyrazole, optionally respectively substituted, and C is selected from O-R2, wherein R2is C1-10alkyl or aryl, or (C1-10alkyl)3Si or (aryl)3Si, respectively substituted with one or more of halogen or CF3, or (C1-10alkyl)3Si or (aryl)3Si is selected from t-butyldimethylsilyl (TBS, TBDMS), trimethylsilyl (TMS), triethylsilyl (TES), triisopropylsilyl (TIPS), t-butyldiphenylsilyl (TBDPS), and triphenylsily; and 1,10-phenanthroline is unsubstituted or is substituted with one or more selected from C1-5 alkyl, C1-5 alkoxy, -O-(CH2)n-O- (n = 1 or 2), and phenyl.

[0062] In one embodiment, B is selected from pyrrole, indole and pyrazole, optionally respectively substituted, and C is selected from (CF3)3CO-, (CCl3)(CF3)2CO-, (C6H5)(CF3)2CO-, (CH3)(CF3)2CO-, ClC6H4O-, Cl2C6H3O-, Cl3C6H2O-, BrC6H4O-, Br2C6H3O-, Br3C6H2O-, CF3C6H4O-, (CF3)2C6H3O-, Cl(CF3)C6H3O-, t- butyldimethylsilyloxy (TBSO, TBDMSO), trimethylsilyloxy (TMSO), triethylsilyloxy (TESO), triisopropylsilyloxy (TIPS)O, t-butyldiphenylsilyloxy (TBDPSO), and triphenylsilyloxy; and 1,10-phenanthroline is unsubstituted or is selected from 4,7-dimethyl-1,10-phenanthroline, 4,7-diphenyl-1,10-phenanthroline, 4,7-dimethoxy-1,10- phenanthroline, 3,8-dimethyl-1,10-phenanthroline, 3,8-dimethoxy-1,10- phenanthroline, 2,9-dimethyl-1,10-phenanthroline, 2,9-dimethoxy-1,10- phenanthroline, 5,6-dimethyl-1,10-phenanthroline, 5,6-diphenyl-1,10-phenanthroline, 5,6-dimethoxy-1,10-phenanthroline, and 1,10-phenanthroline[5,6-d]-1,3-dioxole.

[0063] In one embodiment, B is identical to C, wherein C is selected from O-R2, wherein R2is C1-10 alkyl or aryl, or (C1-10alkyl)3Si or (aryl)3Si, respectively substituted with one or more of halogen or CF3; or (C1-10alkyl)3Si or (aryl)3Si is t-butyldimethylsilyl, trimethylsilyl, triethylsilyl, triisopropylsily, t-butyldiphenylsilyl, or triphenylsilyl; and 1,10- phenanthroline is unsubstituted or is substituted with one or more selected from C1-5 alkyl, C1-5alkoxy, -O-(CH2)n-O- (n = 1 or 2), and phenyl.

[0064] In another embodiment, B is identical to C, wherein C is selected from (CF3)3CO-, (CCl3)(CF3)2CO-, (C6H5)(CF3)2CO-, (CH3)(CF3)2CO-, FC6H4O-, F2C6H3O-, F3C6H2O-, C6F5O-, ClC6H4O-, Cl2C6H3O-, Cl3C6H2O-, BrC6H4O-, Br2C6H3O-, Br3C6H2O-, CF3C6H4O-, (CF3)2C6H3O-, Cl(CF3)C6H3O-, t-butyldimethylsilyloxy, trimethylsilyloxy, triethylsilyloxy, triisopropylsilyloxy, t-butyldiphenylsilyloxy, and triphenylsilyloxy; and 1,10-phenanthroline is unsubstituted or is selected from 4,7- dimethyl-1,10-phenanthroline, 4,7-diphenyl-1,10-phenanthroline, 4,7-dimethoxy-1,10- phenanthroline, 3,8-dimethyl-1,10-phenanthroline, 3,8-dimethoxy-1,10- phenanthroline, 2,9-dimethyl-1,10-phenanthroline, 2,9-dimethoxy-1,10- phenanthroline, 5,6-dimethyl-1,10-phenanthroline, 5,6-diphenyl-1,10-phenanthroline, 5,6-dimethoxy-1,10-phenanthroline, and 1,10-phenanthroline[5,6-d]-1,3-dioxole.

[0065] In another embodiment, B is different from C, wherein both B and C are selected from O-R2, wherein R2is C1-10 alkyl or aryl, or (C1-10alkyl)3Si or (aryl)3Si, respectively substituted with one or more of halogen or CF3; or (C1-10alkyl)3Si or (aryl)3Si is t-butyldimethylsilyl, trimethylsilyl, triethylsilyl, triisopropylsily, t- butyldiphenylsilyl, or triphenylsilyl; and 1,10-phenanthroline is unsubstituted or is substituted with one or more selected from C1-5alkyl, C1-5alkoxy, -O-(CH2)n-O- (n = 1 or 2), and phenyl.

[0066] In another embodiment, B is different from C, wherein both B and C are selected from (CF3)3CO-, (CCl3)(CF3)2CO-, (C6H5)(CF3)2CO-, (CH3)(CF3)2CO-, FC6H4O-, F2C6H3O-, F3C6H2O-, C6F5O-, ClC6H4O-, Cl2C6H3O-, Cl3C6H2O-, BrC6H4O-, Br2C6H3O-, Br3C6H2O-, CF3C6H4O-, (CF3)2C6H3O-, Cl(CF3)C6H3O-, t- butyldimethylsilyloxy, trimethylsilyloxy, triethylsilyloxy, triisopropylsilyloxy, t- butyldiphenylsilyloxy, and triphenylsilyloxy; and 1,10-phenanthroline is unsubstituted or is selected from 4,7-dimethyl-1,10-phenanthroline, 4,7-diphenyl-1,10- phenanthroline, 4,7-dimethoxy-1,10-phenanthroline, 3,8-dimethyl-1,10- phenanthroline, 3,8-dimethoxy-1,10-phenanthroline, 2,9-dimethyl-1,10- phenanthroline, 2,9-dimethoxy-1,10-phenanthroline, 5,6-dimethyl-1,10- phenanthroline, 5,6-diphenyl-1,10-phenanthroline, 5,6-dimethoxy-1,10- phenanthroline, and 1,10-phenanthroline[5,6-d]-1,3-dioxole.

[0067] The inventors of the present invention discovered that such complexes of formula I are non-dissociative in the composition according to the invention at least up to room temperature.

[0068] In the compound (X1) of formula II, said neutral ligand is (b) 2,2’-bipyridine or substituted 2,2’-bipyridine. Both N atoms of the bipyridine scaffold bind to M, thus forming the bidentate ligand, and thus the 18-electron alkylidene compound.

[0069] In a preferred embodiment, 2,2’-bipyridine is independently substituted with one or more of C1-5 alkyl, C1-5 alkoxy, and phenyl. These groups represent electron- donating groups in the meaning of the invention.

[0070] Commercially available bipyridines having electron-donating groups are, e.g., 4,4’-dimethyl-2,2’-bipyridine, 5,5’-dimethyl-2,2’-bipyridine, 4,4’-dimethoxy-2,2’- bipyridine, and 5,5’-dimethoxy-2,2’-bipyridine.

[0071] In a further preferred embodiment, B is identical to C, wherein C is an electron- withdrawing group, and 2,2’-bipyridine is unsubstituted or is substituted with one or more electron-donating groups as defined above.

[0072] In a further preferred embodiment, B is different from C, but both B and C are electron-withdrawing groups, and D is 2,2’-bipyridine or is 2,2’-bipyridine substituted with one or more electron-donating groups as defined above.

[0073] In a preferred embodiment, B is identical to C, wherein C is selected from O- R2, wherein R2is C1-10alkyl or aryl, or (C1-10alkyl)3Si or (aryl)3Si, respectively substituted with one or more of halogen or CF3; or (C1-10alkyl)3Si or (aryl)3Si is selected from t- butyldimethylsilyl (TBS, TBDMS), trimethylsilyl (TMS), triethylsilyl (TES), triisopropylsilyl (TIPS), t-butyldiphenylsilyl (TBDPS), and triphenylsily; and 2,2’- bipyridine is unsubstituted or is 2,2’-bipyridine substituted with one or more selected from C1-5 alkyl, C1-5 alkoxy, and phenyl.

[0074] In a preferred embodiment, B is identical to C, wherein C is selected from (CF3)3CO-, (CCl3)(CF3)2CO-, (C6H5)(CF3)2CO-, (CH3)(CF3)2CO-, FC6H4O-, F2C6H3O-, F3C6H2O-, C6F5O-, ClC6H4O-, Cl2C6H3O-, Cl3C6H2O-, BrC6H4O-, Br2C6H3O-, Br3C6H2O-, CF3C6H4O-, (CF3)2C6H3O-, Cl(CF3)C6H3O-, or t-butyldimethylsilyloxy, trimethylsilyloxy, triethylsilyloxy, triisopropylsilyloxy, t-butyldiphenylsilyloxy, and triphenylsilyoxy; and D is selected from 2,2’-bipyridine, 4,4’-dimethyl-2,2’-bipyridine, 5,5’-dimethyl-2,2’-bipyridine, 4,4’-dimethoxy-2,2’-bipyridine, and 5,5’-dimethoxy-2,2’- bipyridine.

[0075] In a further preferred embodiment, B is different from C, wherein both B and C are selected from O-R2, wherein R2is C1-10 alkyl or aryl, or (C1-10alkyl)3Si or (aryl)3Si, respectively substituted with one or more of halogen or CF3; or (C1-10alkyl)3Si or (aryl)3Si is selected from t-butyldimethylsilyl (TBS, TBDMS), trimethylsilyl (TMS), triethylsilyl (TES), triisopropylsilyl (TIPS), t-butyldiphenylsilyl (TBDPS), and triphenylsily; and D is selected from 2,2’-bipyridine or 2,2’-bipyridine substituted with one or more selected from C1-5alkyl, C1-5alkoxy, and phenyl.

[0076] In a further preferred embodiment, B is different from C, wherein both B and C are selected from (CF3)3CO-, (CCl3)(CF3)2CO-, (C6H5)(CF3)2CO-, (CH3)(CF3)2CO-, FC6H4O-, F2C6H3O-, F3C6H2O-, C6F5O-, ClC6H4O-, Cl2C6H3O-, Cl3C6H2O-, BrC6H4O-, Br2C6H3O-, Br3C6H2O-, CF3C6H4O-, (CF3)2C6H3O-, Cl(CF3)C6H3O-, or t-butyldimethylsilyloxy, trimethylsilyloxy, triethylsilyloxy, triisopropylsilyloxy, t- butyldiphenylsilyloxy, and triphenylsilyoxy; and D is selected from 2,2’-bipyridine, 4,4’- dimethyl-2,2’-bipyridine, 5,5’-dimethyl-2,2’-bipyridine, 4,4’-dimethoxy-2,2’-bipyridine, and 5,5’-dimethoxy-2,2’-bipyridine.

[0077] The inventors of the present invention discovered that such complexes of formula II typically are non-dissociative in the composition according to the invention at room temperature or at least up to room temperature.

[0078] Accordingly, in preferred embodiments, the compositions according to the invention require that the compounds (X1) of formula I and (X2) of formula II comprised therein are non-dissociative in the compositions at least up to room temperature.

[0079] In one embodiment, compound (X1) of formula I or compound (X2) of formula II are termed as non-dissociative in the composition provided their stability constant exceeds a value of 250,000 L*mol-1when measured at 298 K. Further preferred ranges are more than 300,000 L*mol-1or more than 350,000 L*mol-1or more than 400,000 L*mol-1when measured at 298 K. The stability constant can be determined according to known methods employing the law of mass action. Reference is made to WO 2021 / 239891 as referred to in the Background section.

[0080] Complexes with a virtually infinite stability constant K, i.e., with a stability constant being too high in a predetermined solvent such as in the compound (X2) are too stable to release the active form therefrom. This applies to the complexes needing the assistance of a Lewis acid to remove the bidentate ligand as are known from the prior art as referred to in the Background section.

[0081] In another embodiment, the non-dissociative character of compounds (X1) of formula I or (X2) of formula II can be verified by1H NMR-spectroscopic methods as is apparent from the referenced prior art (J. Heppekausen and A. Fürstner) as referred to in the Background section.

[0082] The1H NMR spectra of Fig.1 to 3 show that when heating the phenanthroline complexknown from Heppekausen and Fürstner as referred to in the Background section, the complex remains non-dissociated at least up to a temperature of 95 °C. After cooling, the spectrum of Fig.4 is identical to the spectrum of Fig.1. Shifts in the aliphatic region (isopropyl, methyl) are temperature effects.

[0083] A possible dissociation would be detectable by means of the chemical shift of the alkylidene proton, which is different for the 18-electron complex and the 14-electron complex. A possible (partly) dissociation may also be quantitatively recorded by means of1H NMR-spectroscopy. Respective methods are known in the art.

[0084] According to the invention, when the temperature is above 50 °C, there is no need to add a Lewis acid such as zinc chloride to the complex of formula I or formula II to remove the bidentate ligand from the complex to form the activated 14-electron complex from the 18-electron complex. Rather, the complexes of formula I or formula II are thermoactivated, i.e., without the need of chemical activation. Surprisingly, even when no dissociation at that higher temperature of above 50 °C may be observed by NMR analysis, the thermoactivated catalyst of formula I or formula II initiates a metathesis reaction. This could not be expected in view of the hitherto assumption that only the compound being devoid of the neutral bidentate ligand is active (see J. Heppekausen and A. Fürstner as referred to in the Background section).

[0085] WO2021 / 239891 provides a guidance as to the tailor-made synthesis of non- dissociative complexes. This document namely discloses how the stability constant of the complexes may be influenced by the appropriate choice of the ligands in the complex. The inventors discovered that by means of the substitution pattern in particular in terms of at least D (1,10-phenanthroline and substituted 1,10 phenanthroline) or further ligands B and C such as alkoxide, aryloxide or D and C, thestability constant K with respect to the neutral bidentate ligand in a solvent may be adjusted to a range of from 5 L*mol-1to 250,000 L*mol-1when measured at 298 K when the complex is dissolved in the solvent in order to release the active form, namely the 14-electron complex, from the 18-electron complex.

[0086] WO2021 / 239891 discloses in one embodiment that 1,10-phenanthroline is substituted with one or more electron-donating groups in order to increase the stability constant compared to a complex having the same substitution pattern in terms of A, B, and C but in which the bidentate ligand is unsubstituted 1,10-phenanthroline. In another embodiment, 1,10-phenanthroline is substituted with one or more electron- withdrawing groups in order to decrease the stability constant compared to a complex having the same substitution pattern in terms of A, B, and C but in which the bidentate ligand is unsubstituted 1,10-phenanthroline.

[0087] In another embodiment, the steric bulk, i.e., the spatial expansion of the residue C is increased in order to decrease the stability constant compared to a complex having the same substitution pattern in terms of A, B, and D. In another embodiment, the steric bulk, i.e., the spatial expansion of the residue C, is decreased in order to increase the stability constant compared to a complex having the same substitution pattern in terms of A, B, and D.

[0088] Accordingly, said methods defined in WO 2021 / 239891 may also be used for the tailor-made preparation of non-dissociative complexes of the compounds defined in the present invention under formulae I and II.

[0089] The content of WO 2021 / 239891 is incorporated herein by reference in its entirety.

[0090] The term “room temperature” as used herein defines a temperature up to 25 °C, preferably 15 to 25 °C. The term “room temperature” is synonymously used with the term “ambient temperature”.

[0091] The term “at least up to room temperature” as used herein with respect to the compound (X1) of formula I and the compound (X2) of formula II encompasses atemperature above 25 °C. Thus, the term may be synonymously used with the term “at least up to room temperature and above”.

[0092] In one embodiment, the compound (X1) of formula I or (X2) of formula II is non-dissociative up to a temperature of at least 50 °C or 60 °C or 70 °C or 80 °C or 100 °C or 120 °C or above.

[0093] In one embodiment, R3and R4are independently H, C1-10 alkyl or aryl, wherein C1-10 alkyl or aryl are independently substituted with one or more of C1-5 alkyl, C1-5 alkyl substituted with one or more of halogen, C1-5alkoxy, phenyl, halogen.

[0094] In one embodiment, the temperature of the composition according to the invention is above 55 °C or above 60 °C or above 70 °C or above 80 °C or above 90 °C or above 100 °C; or the temperature is in a range of from above 50 to 140 °C or above 55 to 130 °C or above 60 to 120 °C.

[0095] According to the invention, the composition does not contain a Lewis acid.

[0096] In one embodiment, the molar ratio of compound(s) (Y) comprising one or more compounds comprising an olefinic double bond to the compound (X1) of formula I or (X2) of formula II in a composition which has a temperature of 50 °C or below is greater than 2000 or 4000 or 6000 or 8000 or 10,000 or 20,000 or 30,000 or 40,000 compared to the composition which has the temperature above 50 °C.

[0097] According to a preferred embodiment, the composition does not contain an inert solvent for the compound (X) and / or (Y). However, as used herein, this term does not exclude that minor amounts of an inert solvent are used to handle compounds (X1) or (X2). The term “wherein the composition does not contain an inert solvent for the compound (X) and / or (Y)” as used herein thus encompasses that an inert solvent such as benzene or toluene or chlorobenzene or a hydrocarbon may be present in the composition, wherein the molar ratio of the one or more compound(s) each comprising an olefinic double bond to the inert solvent is greater than 200 or greater than 500 or greater than 1000 or greater than 2000.

[0098] Thus, in a preferred embodiment, the compound (Y) is the solvent, wherein the solvent does not comprise a further solvent, e.g., an inert solvent such as benzene or toluene or chlorobenzene or a hydrocarbon.

[0099] In one embodiment, the compound of formula I is selected from one of the following compounds 5 to 8:wherein R24= methyl, phenyl; R25, R26= H, methyl, CF3; Z =methyl, iso-propyl, halogen; or is selected from one of the following compounds III to VIor is selected from one of the following compounds:R = Me, Ph; Ar = 2,6-diisopropylphenyl;; or wherein the compound of formula II is selected from.

[0100] Method of making the compositions according to the invention

[0101] The invention further relates to a method of making a composition according to the invention, the method comprising: providing a compound (X) (or a compound (X1) of formula I or a compound (X2) of formula II) and one or more compound(s) (Y); heating a mixture of the provided compounds to a temperature above 50 °C; wherein the composition does not contain one or more of MgCl2, MgBr2, MgI2, MnCl2, MnBr2, MnI2, FeCl3, AlCl3, CuCl2, ZnCl2, ZnBr2, ZnI2, Zn(triflate)2 or Zn(trifluoroacetate)2; preferably wherein the composition does not contain an inert solvent for the compound (X) and / or (Y).

[0102] Method of thermoactivating

[0103] The invention further relates to a method of activating a compound (X) (or (X1) of formula I or (X2) of formula II as defined above) for initiating an olefinic metathesis reaction in a composition comprising one or more compound(s) (Y), the method comprising: heating a composition comprising the compounds (X) (or (X1) and (X2)) and (Y) to a temperature above 50 °C; wherein the composition does not contain one or more of MgCl2, MgBr2, MgI2, MnCl2, MnBr2, MnI2, FeCl3, AlCl3, CuCl2, ZnCl2, ZnBr2, ZnI2, Zn(triflate)2 or Zn(trifluoroacetate)2; preferably wherein the composition does not contain an inert solvent for the compound (X) and / or (Y).

[0104] The invention further relates to a method of performing a metathesis reaction, the method comprising: heating a composition comprising a compound (X) (or (X1) of formula I or (X2) of formula II) with one or more compounds (Y), to a temperature above 50 °C, wherein the composition does not contain one or more of MgCl2, MgBr2, MgI2, MnCl2, MnBr2, MnI2, FeCl3, AlCl3, CuCl2, ZnCl2, ZnBr2, ZnI2, Zn(triflate)2 or Zn(trifluoroacetate)2; preferably wherein the composition does not contain an inert solvent for the compound (X) and / or (Y).

[0105] Further subject-matter

[0106] The invention further relates to a composition, comprising: a compound (X) (or a compound (X1) of formula I or a compound (X2) of formula II) as defined above;one or more compound(s) (Y) each comprising an olefinic double bond; wherein the composition does not contain one or more of MgCl2, MgBr2, MgI2, MnCl2, MnBr2, MnI2, FeCl3, AlCl3, CuCl2, ZnCl2, ZnBr2, ZnI2, Zn(triflate)2 or Zn(trifluoroacetate)2; wherein the composition has a temperature below 50 °C; preferably wherein the composition does not contain an inert solvent for the compound (X) and / or (Y).

[0107] The invention further relates to the use of said composition in a metathesis reaction, the use comprising: heating the composition above a temperature of 50 °C.

[0108] The invention further relates to the use of a compound (X) (or a compound (X1) of formula I or a compound (X2) of formula II as defined above) for initiating a metathesis reaction in one or more compound(s) (Y) each comprising an olefinic double bond, the use comprising: heating a composition comprising the compounds (X) (or (X1) and (X2)) and (Y) to a temperature above 50 °C; wherein the composition does not contain one or more of MgCl2, MgBr2, MgI2, MnCl2, MnBr2, MnI2, FeCl3, AlCl3, CuCl2, ZnCl2, ZnBr2, ZnI2, Zn(triflate)2 or Zn(trifluoroacetate)2; preferably wherein the composition does not contain an inert solvent for the compound (X) and / or (Y).

[0109] The composition according to the invention can be used in all kinds of olefin metathesis reactions.

[0110] In one embodiment, in the composition according to the invention the one or more compounds each comprising an olefinic double bond are selected such toperform a cross-metathesis reaction (CM) including self- metathesis [(homo)-cross metathesis (HCM)].

[0111] In another embodiment, in the composition according to the invention the one or more compounds each comprising an olefinic double bond are selected such to perform a ring-closing metathesis reaction (RCM).

[0112] In another embodiment, in the composition according to the invention the one or more compounds each comprising an olefinic double bond are selected such to perform a ring-opening metathesis reaction (ROM).

[0113] In another embodiment, in the composition according to the invention the one or more compounds each comprising an olefinic double bond are selected such to perform a ring-opening metathesis polymerization (ROMP).

[0114] In another embodiment, in the composition according to the invention the one or more compounds each comprising an olefinic double bond are selected such to perform an acyclic diene metathesis reaction (ADMET).

[0115] The invention further relates to the following items: 1. Composition capable of performing a metathesis reaction, the composition comprising: (X) a 14-electron Schrock alkylidene compound complexed with a bidentate ligand selected from (a) a 1,10-phenanthroline (optionally substituted) and (b) a 2,2’-bipyridine (optionally substituted); to form a 18-electron alkylidene compound; and (Y) one or more compounds each comprising an olefinic double bond;wherein the composition (c) does not contain a Lewis acid selected from one or more of MgCl2, MgBr2, MgI2, MnCl2, MnBr2, MnI2, FeCl3, AlCl3, CuCl2, ZnCl2, ZnBr2, ZnI2, Zn(triflate)2 or Zn(trifluoroacetate)2; (d) is at a temperature above 50 °C; (e) contains an inert solvent for the compounds (X) and / or (Y). Composition of item 1, comprising: (X1) a compound of formula II wherein M is Mo or W; A is selected from N-R1or O, wherein R1is C1-10 alkyl or aryl, optionally respectively substituted; B is selected from pyrrole, indole and pyrazole, optionally respectively substituted; and C is selected from O-R2, wherein R2is C1-10 alkyl or aryl, or (C1-10alkyl)3Si or (aryl)3Si, optionally respectively substituted; or B is identical to C, wherein C is selected from O-R2, wherein R2is C1-10alkyl or aryl, or (C1-10alkyl)3Si or (aryl)3Si, optionally respectively substituted; orB is different from C, wherein both B and C are selected from O-R2, wherein R2is C1-10alkyl or aryl, or (C1-10alkyl)3Si or (aryl)3Si, optionally respectively substituted; D is 1,10-phenanthroline or substituted 1,10-phenanthroline; R3and R4are independently H, C1-10alkyl or aryl, C1-10alkyl and aryl being optionally substituted; and wherein only one of R3and R4is hydrogen; or comprising (X2) a compound of formula IIwherein M is Mo or W; A is selected from N-R1or O, wherein R1is C1-10 alkyl or aryl, optionally respectively substituted; B is selected from pyrrole, indole and pyrazole, optionally respectively substituted; and C is selected from O-R2, wherein R2is C1-10 alkyl or aryl, or (C1-10alkyl)3Si or (aryl)3Si, optionally respectively substituted; or B is identical to C, wherein C is selected from O-R2, wherein R2is C1-10alkyl or aryl, or (C1-10alkyl)3Si or (aryl)3Si, optionally respectively substituted; orB is different from C, wherein both B and C are selected from O-R2, wherein R2is C1-10alkyl or aryl, or (C1-10alkyl)3Si or (aryl)3Si, optionally respectively substituted; D is 2,2’-bipyridine or substituted 2,2’-bipyridine; R3and R4are independently H, C1-10alkyl or aryl, C1-10alkyl and aryl being optionally substituted; and wherein only one of R3and R4is hydrogen. 3. Composition of item 2, wherein R1is C1-10 alkyl or phenyl, respectively independently substituted with one or more of C1-10alkyl, C1-10alkoxy, phenyl, halogen, CN, and CF3. 4. Composition of any one of items 2 to 3, wherein B is selected from pyrrole, indole and pyrazole, respectively independently substituted with one or more of C1-10alkyl, C1-10alkoxy or phenyl. 5. Composition of any one of items 2 to 4, wherein R2is selected from C1-10 alkyl or phenyl, optionally substituted. 6. Composition of any one of items 1 to 5, wherein the compound (X) or the compound (X1) and (X2) is / are non-dissociative in the composition at least up to room temperature. 7. Composition of any of items 2 to 6 as far as referring back to claim 2, wherein C is an electron-withdrawing group, and 1,10-phenanthroline is unsubstituted; or C is an electron-withdrawing group, and 1,10-phenanthroline is substituted with one or more electron-donating groups; or B is identical to C, wherein C is an electron-withdrawing group, and 1,10- phenanthroline is unsubstituted; or B is identical to C, wherein C is an electron-withdrawing group, and 1,10- phenanthroline is substituted with one or more electron-donating groups; orB is different from C, wherein both B and C are electron-withdrawing groups, and 1,10-phenanthroline is unsubstituted; or B is different from C, wherein both B and C are electron-withdrawing groups, and 1,10-phenanthroline is substituted with one or more electron-donating groups; B is identical to C, wherein C is an electron-withdrawing group, and 2,2’-bipyridine is unsubstituted; or B is identical to C, wherein C is an electron-withdrawing group, and 2,2’-bipyridine is substituted with one or more electron-donating groups; B is different from C, wherein both B and C are electron-withdrawing groups, and 2,2’-bipyridine is unsubstituted; or B is different from C, wherein both B and C are electron-withdrawing groups, and 2,2’-bipyridine is substituted with one or more electron-donating groups; preferably wherein B is selected from pyrrole, indole and pyrazole, optionally respectively substituted, and C is selected from O-R2, wherein R2is C1-10alkyl or aryl, or (C1-10alkyl)3Si or (aryl)3Si, respectively substituted with one or more of halogen or CF3; or B is identical to C, wherein C is selected from O-R2, wherein R2is C1-10alkyl or aryl, or (C1-10alkyl)3Si or (aryl)3Si, respectively substituted with one or more of halogen or CF3; and 1,10-phenanthroline is unsubstituted or is 1,10- phenanthroline substituted with one or more selected from C1-5alkyl, C1-5alkoxy, -O-(CH2)n-O- (n = 1 or 2), and phenyl; or B is identical to C, wherein C is selected from O-R2, wherein R2is C1-10 alkyl or aryl, or (C1-10alkyl)3Si or (aryl)3Si, respectively substituted with one or more of halogen or CF3; and 2,2’-bipyridine is unsubstituted or is substituted with one or more selected from C1-5 alkyl, C1-5 alkoxy, or phenyl.Composition of any one of items 1 or 7, wherein the compound (X) (or (X1) and (X2)) is non-dissociative up to a temperature of 50 °C. Composition of any one of items 2 to 8, wherein R3and R4are independently H, C1-10 alkyl or aryl, wherein C1-10 alkyl or aryl are independently substituted with one or more of C1-5alkyl, C1-5alkyl substituted with one or more of halogen, C1-5alkoxy, phenyl, halogen. Composition of any one of items 1 to 9, wherein the molar ratio of compound(s) (Y) comprising one or more compounds each comprising an olefinic double bond to the compound (X) or (X1) of formula I or to the compound (X2) of formula II in a composition which has a temperature of 50 °C or below is greater than 2000 or 4000 or 6000 or 8000 or 10,000 or 20,000 or 30,000 or 40,000 compared to the composition which has the temperature above 50 °C. Composition of any one of items 1 to 10, wherein the temperature is above 55 °C or above 60 °C or above 70 °C or above 80 °C or above 90 °C or above 100 °C; or wherein the temperature is in a range of from above 50 to 140 °C or above 55 to 130 °C or above 60 to 120 °C. Composition of any of items 1 to 11, wherein the compound (X) is selected from one of the following compounds 5 to 8:wherein R24= methyl, phenyl; R25, R26= H, methyl, CF3; Z =methyl, iso-propyl, halogen; or is selected from one of the following compounds III to VIor is selected from one of the following compounds:R = Me, Ph; Ar = 2,6-diisopropylphenyl;; or is selected from. Method of making a composition as defined in any one of items 1 to 12, the method comprising: providing a compound (X) and a compound (Y); heating a mixture of the provided compounds to a temperature above 50 °C; wherein the composition does not contain a Lewis acid selected from one or more of MgCl2, MgBr2, MgI2, MnCl2, MnBr2, MnI2, FeCl3, AlCl3, CuCl2, ZnCl2, ZnBr2, ZnI2, Zn(triflate)2 or Zn(trifluoroacetate)2; and wherein the composition contains an inert solvent for the compounds (X) and / or (Y). Method of activating a compound (X) as defined in any one of items 1 to 12 for initiating an olefinic metathesis reaction in a composition comprising one or more compound(s) (Y) each comprising an olefinic double bond, the method comprising: heating a composition comprising the compounds (X) and (Y) to a temperature above 50 °C; whereinthe composition does not contain a Lewis acid selected from one or more of MgCl2, MgBr2, MgI2, MnCl2, MnBr2, MnI2, FeCl3, AlCl3, CuCl2, ZnCl2, ZnBr2, ZnI2, Zn(triflate)2 or Zn(trifluoroacetate)2; and wherein the composition contains an inert solvent for the compounds (X) and / or (Y). Method of performing a metathesis reaction, the method comprising: heating a composition comprising a compound (X) and one or more compounds (Y) as defined in any one of items 1 to 12 to a temperature above 50 °C, wherein the composition does not contain a Lewis acid selected from one or more of MgCl2, MgBr2, MgI2, MnCl2, MnBr2, MnI2, FeCl3, AlCl3, CuCl2, ZnCl2, ZnBr2, ZnI2, Zn(triflate)2 or Zn(trifluoroacetate)2; and wherein the composition contains an inert solvent for the compounds (X) and / or (Y). Composition, comprising: a compound (X) and one or more compounds (Y) as defined in any one of items 1 to 12; wherein the composition does not contain a Lewis acid selected from one or more of MgCl2, MgBr2, MgI2, MnCl2, MnBr2, MnI2, FeCl3, AlCl3, CuCl2, ZnCl2, ZnBr2, ZnI2, Zn(triflate)2or Zn(trifluoroacetate)2; wherein the composition has a temperature below 50 °C; and wherein the composition contains an inert solvent for the compounds (X) and / or (Y).17. Use of the composition as defined in item 16 in a metathesis reaction, the use comprising: heating the composition above a temperature of 50 °C; wherein the composition contains an inert solvent for the compounds (X) and / or (Y). 18. Use of a compound (X) for initiating a metathesis reaction in a composition comprising one or more compound(s) (Y) as defined in any one of item 1 to 12, the use comprising: heating a composition comprising the compounds (X) and (Y) to a temperature above 50 °C; wherein the composition does not contain a Lewis acid selected from one or more of MgCl2, MgBr2, MgI2, MnCl2, MnBr2, MnI2, FeCl3, AlCl3, CuCl2, ZnCl2, ZnBr2, ZnI2, Zn(triflate)2or Zn(trifluoroacetate)2; wherein the composition contains an inert solvent for the compounds (X) and / or (Y).

[0116] The invention also relates to the compositions, methods and uses including the respective embodiments as described herein, wherein the compound (X) has a stability constant which exceeds a value of 250,000 L*mol-1at 298 K in a solvent, wherein the solvent is the one or more compounds (Y) each comprising an olefinic double bond, and / or wherein the solvent is an inert solvent for the compound (X) and / or (Y), the stability constant being determined as defined in this description.

[0117] In preferred embodiments, the stability constant is more than 300,000 L*mol-1or more than 350,000 L*mol-1or more than 400,000 L*mol-1.

[0118] In one embodiment, the stability constant is less than 2,000,000 L*mol-1.

[0119] In a preferred embodiment, the stability constant is less than 1,000,000 L*mol-1.EXEMPLIFICATION PREPARATION EXAMPLES

[0120] The complexes used in the following examples are known or can be prepared according to known methods as disclosed in the references mentioned in the Background section or known from Schrock publications.

[0121] Example 1:

[0122] A mixture of dimethyl diallyl malonateandwas stirred in a vial equipped with pierced septum for ethylene release without additional solvent at a temperature of 70 °C for 13 h at a catalyst loading of 1,000 ppm to yield more than 99 % ofas confirmed by1H NMR and GC analysis.

[0123] Example 2

[0124] A mixture of 1-deceneandwas stirred in a vial equipped with pierced septum for ethylene release without additional solvent at a temperature of 70 °C for 13 h at a catalyst loading of 1,000 ppm to yield 85 % (cis / trans mixture) ofas confirmed by1H NMR and GC analysis.

[0125] Example 3

[0126] The experiments disclosed in the following Table 1 were performed with catalyst 2 referring to.Entry 4 shows that the catalyst is non-active at room temperature, whereas the catalyst may be activated at higher temperature.

[0127] Example 4

[0128] Table 2 shows a comparison of non-dissociative catalyst 2 with 14-electron catalysts 1, 5, and 6 and dissociative complex 4 in the ring-opening metathesis polymerization (ROMP) of DCPD when DCPD and the catalyst are mixed at room temperature (RIM = reaction injection molding).Table 2Initiator Scale DCPD:initiatorbPolymer d ratio Mixing Onset yieldcTg 5 148 mmol 10000 homogeneous immediate 97% 132 °C 5 148 mmol 20000 homogeneous 2 min. 95% 141 °C 5 148 mmol 40000 homogeneous - 73% - 6 148 mmol 10000 homogeneous 1 min. 98% 159 °C 6 148 mmol 20000 homogeneous 3 min. 70% - 6 148 mmol 40000 homogeneous - 32% - 1 37 mmol 10000 immediate encapsulation - - - 4 37 mmol 10000 immediate encapsulation - - - 2 37 mmol 10000 homogeneous 6 min. 97% n.d. 2 74 mmol 20000 homogeneous 10 min. 95% 160 °C 2 148 mmol 40000 homogeneous 15 min. 95% 154 °C 2 111 mmol 60000 homogeneous 15 min. 98% 160 °C 2 74 mmol 80000 homogeneous 21 min. 95% 142 °C 2 74 mmol 100000 homogeneous 34 min. 91% 122 °CaGeneral: The reactions were carried out in 30-mL vials sealed with septa. The initiators were applied in a 0.037 M PhCl stock solution. The RIM monomer was added to the initiator stock solution to increase mixing efficiency. (Reversed setup resulted in encapsulation in the case of 5.) After mixing the RIM monomer and the initiator stock solution at room temperature, the mixture was left to react without stirring or heating. Due to the exothermicity of DCPD ROMP and the high reaction rates, high-yielding ROMPs were always accompanied by rapid temperature rise after onset.bThe onset was defined as the point when the reaction mixture becomes non-fluid, and the temperature starts rising sharply. (The two phenomena typically occur parallel.)cDetermined by thermogravimetric analysis of the polymers.dGlass transition temperature.

[0129] It is striking that 14-electron catalysts 1, 5, and 6 cause reaction at room temperature within very short onset times, i.e., when the reaction mixture becomes non-fluid due to starting polymerization and the temperature starts rising sharply exceeding a temperature far beyond 100 °C due to the exothermicity of the reaction.

[0130] With dissociative (autoactivating) catalyst 4, due to a spontaneous reaction, no homogeneous mixing could be achieved due to the high reactivity of DCPD. The reaction resulted in an inhomogeneous product, probably due to encapsulation and / or degradation of the catalyst. The same applies to catalyst 1.

[0131] Contrary to complexes 1, 4, 5, and 6, non-dissociative complex 2 resulted in a prolonged onset. Although the complex 2 is non-dissociative at room temperature, i.e., the complex is thermodynamically stable, without being bound by theory, the inventors of the present invention assume that the observed smooth reaction at room temperature with a prolonged onset time can be explained with the presence of traces of compound 1 in the adduct 2. These traces present in the DCPD can initiate a ROMP reaction with the very reactive olefin. The high exothermicity of the reaction provides sufficient heat to heat the composition far above a temperature of 50 °C leading to nearly complete conversion of the DCPD.

[0132] Example 5

[0133] Table 3 shows a ROMP reaction of DCPD using a non-dissociative phenanthroline complex:(above compound 3 is identical to compound 2 disclosed in Heppekausen and Fürstner as referred to in the Background section)

[0134] Example 6 Table 4 shows the ring-opening metathesis polymerization of “extra pure” 1,5-cis,cis- cyclooctadiene (COD), promoted by 2 (compound 2 is identical to compound 3 disclosed in Heppekausen and Fürstner as referred to in the Background sectionin the absence of Lewis acidic activators:Table 4 substrate scale substrate:2 stirring t reaction ratio emperature time Conversion cyclooctadiene 8.2 mmol 20000 no 70 °C 24 h >99%cyclooctadiene mmol 40000 no 70 °C 24 h >99% cyclooctadiene 24.5 mmol 60000 no 70 °C 24 h >99% General: “extra pure” COD was thoroughly purified by 24h refluxing under argon atmosphere over calcium hydride prior distillation. The distilled COD was extra dried with activated 3A molecular sieves for at least 24h before filtration and storage. The reactions were carried out in 4-mL vials sealed with septa.2 was delivered in a 0.037 M PhCl stock solution in the vial and the substrate was added to it. No additional solvent was used in any of the reactions. The vials were heated in an aluminum heating block at 70 °C for the given reaction times. Conversions were determined by1H NMR analysis.

[0135] Example 7

[0136] This example shows additional experimental evidence of the thermal activation of Mo(NArdiiPr)(CHCMe2Ph)(OC(CF3)2Me)2(2,2’-bipyridine) 2

[0137] 1. Van’t Hoff analysis

[0138] In line with Fürstner’s findings and claims (doi.org / 10.1002 / anie.201102012 and WO 2012 / 116695 as referred to in the Background section), Mo(NArdiiPr)(CHCMe2Ph)(OC(CF3)2Me)2(2,2’-bipyridine) 2 and Mo(NArdiiPr)(CHCMe2Ph)(OC(CF3)2Me)2(1,10-phenanthroline) 3 as shown in the below scheme were also found non-dissociative at room temperature (298 K), based on their1H NMR spectra, preventing us from determining the thermodynamic stabilities (stability constants) of these complexes. However, we proved that the bipyridine adduct 2 becomes dissociative even at moderately increased temperatures. The discovery allowed us to experimentally establish the equilibrium constants of 2 at elevated temperatures (from >30 Celsius) and, subsequently, estimate its stability constant at room temperature.Scheme. Schrock catalyst Mo(NArdiiPr)(CHCMe2Ph)(OC(CF3)2Me)21 and its notable 18-electron adducts (above compound 2 is identical to compound 3 in Fürstner’s scheme as referred to in the Background section; above compound 3 is identical to compound 2 in Fürstner’s scheme as referred to in the Background section)

[0139] The equilibrium constants of Mo(NArdiiPr)(CHCMe2Ph)(OC(CF3)2Me)2(2,2’- bipyridine) 2 were determined as the function of the temperature in the temperature range from 306.60 K to 372.95 K with approximately 11 K increments between experiments. (Entries 2-8, Table 5.) The equilibrium constants (or stability constants), at each temperature, were determined based on the degree of dissociation of adduct 2, that is, based on the mol fractions of 2 and the corresponding liberated 14-electron complex Mo(NArdiiPr)(CHCMe2Ph)(OC(CF3)2Me)21 in the1H NMR sample (0.0101 M, toluene-d8). The determined lnK values were plotted against the corresponding 1 / T values (Figure 5). The two data sets show the expected linear relationship inaccordance with the linear form of the Van’t Hoff equation (linear form: ^^^ = −+^ ; K - equilibrium constant, DHr- standard reaction enthalpy, DSr- standard reaction entropy). The slope of the line is positive, showing that the net enthalpy change of the coordination of the 2,2’-bipyridine to 1 is negative, the formation of 2 is an exothermic reaction.

[0140] Using the linear relationship shown in Figure 5, extrapolation was used to determine the stability constant at 25 Celsius / 298 K: Ktoluene-d8, 298K= 984609 M-1(Entry1, Table 5). The value is well over the upper limit of the range of stability constants used for the definition of the room-temperature-dissociative („autoactivating”) 18- electron adducts of Schrock catalysts described in GB 2537416, WO2021 / 239891, and doi.org / 10.1038 / s42004-021-00503-4. Notice, however, that as the temperature increases, the stability constant of 2 drops significantly, reaching 161 M-1at 372.9K (Entry 8, Table 5), which means a >50% dissociation of 2 into the catalytically active 1 and 2,2’-bipyridine under the conditions of the1H NMR experiment (0.0101 M, toluene- d8, 272.9K).

[0141] Table 5 below shows stability constants of Mo(NArdiiPr)(CHCMe2Ph)(OC(CF3)2Me)2(2,2’-bipyridine) 2 as the function of the temperature, based on molar ratios of 2 and the corresponding 14-electron complex Mo(NArdiiPr)(CHCMe2Ph)(OC(CF3)2Me)21, determined by1H NMR experiments (0.0101 M, toluene-d8 solution). At 298.15 K the dissociation is negligible, the corresponding stability constant was determined by extrapolation.8 measured 372.951 1611. Homo-cross-metathesis of 9-DAME using „thermoactivating” Mo(NArdiiPr)(CHCMe2Ph)(OC(CF3)2Me)2(2,2’-bipyridine) 2 and „autoactivating” Mo(NArdiiPr)(CHCMe2Ph)(OC(CF3)2Me)2(4,4-dibromo-2,2’-bipyridine) 4

[0142] Homo-cross-metathesis of methyl 9-decenoate (9-DAME) was chosen as model reaction to demonstrate the distinctly different catalytic behaviors of the „thermoactivating” Mo(NArdiiPr)(CHCMe2Ph)(OC(CF3)2Me)2(2,2’-bipyridine) 2 and „autoactivating” Mo(NArdiiPr)(CHCMe2Ph)(OC(CF3)2Me)2(4,4-dibromo-2,2’-bipyridine) 4. Note that 2 is non-dissociative at room temperature, and it was described by Fürstner as inactive in the absence of Lewis acids. Fürstner claimed that Lewis acids must be added to 2 to distract the 2,2’-bipyridine ligand from the adduct hence liberating the active Mo(NArdiiPr)(CHCMe2Ph)(OC(CF3)2Me)21. Mo(NArdiiPr)(CHCMe2Ph)(OC(CF3)2Me)2(4,4-dibromo-2,2’-bipyridine) 4 was developed by XiMo and was structurally tuned to be dissociative at room temperature, capable of liberating the active Mo(NArdiiPr)(CHCMe2Ph)(OC(CF3)2Me)21 in the absence of Lewis acids and consequently being able to catalyze olefin metathesis reactions without the addition of Lewis acids. In accordance with the well-described non-dissociative nature of 2, the adduct did not provide any noticeable conversion of 9-DAME at 21 °C, after 2 hours of reaction time (Entry 1, Table 6), and the conversion remained negligible over the 24-hour observation period (7% after 24 hours, Entry 3, Table 6). Under the same conditions, the room-temperature-dissociative („autoactivating”) 4 provided 28% conversion after 2 hours, and 72% conversion after 24 hours (Entries 2 and 4, Table 6), demonstrating a striking difference between the two adducts despite their analogous structure, and proving the earlier developed concept of „autoactivation”.

[0143] Even more importantly, the reactions performed at 70 °C perfectly demonstrate the concept of „thermoactivation” claimed in the current application. At the elevated temperature, 2 also becomes dissociative, hence catalytically active, and provides very similar performance to the „autoactivating” 4. After one hour of reaction time, the yield of the homo-cross-metathesis product is 89% in the case of 2 and 98% in the case of 4, while after two hours it is 96% for 2 and 99% for 4. (Entries 5, 6 and 8, 9, Table 6) The similar E:Z ratios are indicative of the fact that both precatalystsrelease the same active species 1. It is also noteworthy that both adducts outperform the catalytically active parent complex 1, displaying the role of chemical protection of the N-heterocyclic Lewis bases 2,2’-bipyridine and 4,4’-dibromo-2,2’-bipyridine. (Entries 7, 10 vs.5, 6, 8, 9, Table 6)

[0144] Table 6. Homo-cross-metathesis of methyl 9-decenoate (9-DAME)E- Z- Entry Catalyst Temperature Time Yield isomer isomer 1 2 21 °C 2 h 0% - - 2 4 21 °C 2 h 28% 61% 39% 3 2 21 °C 24 h 7% 63% 37% 4 4 21 °C 24 h 72 % 65% 35% 5 2 70 °C 1 h 98% 78% 22% 6 4 70 °C 1 h 89% 72% 28% 7 1 70 °C 1 h 87% 79% 21% 8 2 70 °C 2 h 99% 78% 22% 9 4 70 °C 2 h 96% 74% 26% 10 1 70 °C 2 h 89% 78% 22% Conditions: 9-DAME: 500 mg / 560 microL, catalyst 300 mol ppm added from 0.0035 M benzene stock solution, open vial for ethylene release; the reaction mixture was stirred at the given temperature for the given reaction time; the samples taken from the reaction mixture were analyzed by GC.

Claims

CLAIMS 1. Composition capable of performing a metathesis reaction, the composition comprising: (X) a 14-electron Schrock alkylidene compound complexed with a bidentate ligand selected from (a) a 1,10-phenanthroline (optionally substituted) and (b) a 2,2’-bipyridine (optionally substituted); to form a 18-electron alkylidene compound; and (Y) one or more compounds each comprising an olefinic double bond; wherein the composition (c) does not contain a Lewis acid selected from one or more of MgCl2, MgBr2, MgI2, MnCl2, MnBr2, MnI2, FeCl3, AlCl3, CuCl2, ZnCl2, ZnBr2, ZnI2, Zn(triflate)2or Zn(trifluoroacetate)2; (d) is at a temperature above 50 °C; preferably wherein the composition (e) does not contain an inert solvent for the compound (X) and / or (Y).

2. Composition of claim 1, comprising: (X1) a compound of formula II wherein M is Mo or W; A is selected from N-R1or O, wherein R1is C1-10 alkyl or aryl, optionally respectively substituted; B is selected from pyrrole, indole and pyrazole, optionally respectively substituted; and C is selected from O-R2, wherein R2is C1-10 alkyl or aryl, or (C1-10alkyl)3Si or (aryl)3Si, optionally respectively substituted; or B is identical to C, wherein C is selected from O-R2, wherein R2is C1-10alkyl or aryl, or (C1-10alkyl)3Si or (aryl)3Si, optionally respectively substituted; or B is different from C, wherein both B and C are selected from O-R2, wherein R2is C1-10alkyl or aryl, or (C1-10alkyl)3Si or (aryl)3Si, optionally respectively substituted; D is 1,10-phenanthroline or substituted 1,10-phenanthroline; R3and R4are independently H, C1-10alkyl or aryl, C1-10alkyl and aryl being optionally substituted; and wherein only one of R3and R4is hydrogen; or comprising (X2) a compound of formula IIII wherein M is Mo or W; A is selected from N-R1or O, wherein R1is C1-10alkyl or aryl, optionally respectively substituted; B is selected from pyrrole, indole and pyrazole, optionally respectively substituted; and C is selected from O-R2, wherein R2is C1-10 alkyl or aryl, or (C1-10alkyl)3Si or (aryl)3Si, optionally respectively substituted; or B is identical to C, wherein C is selected from O-R2, wherein R2is C1-10alkyl or aryl, or (C1-10alkyl)3Si or (aryl)3Si, optionally respectively substituted; or B is different from C, wherein both B and C are selected from O-R2, wherein R2is C1-10alkyl or aryl, or (C1-10alkyl)3Si or (aryl)3Si, optionally respectively substituted; D is 2,2’-bipyridine or substituted 2,2’-bipyridine; R3and R4are independently H, C1-10alkyl or aryl, C1-10alkyl and aryl being optionally substituted; and wherein only one of R3and R4is hydrogen.

3. Composition of claim 2, wherein R1is C1-10 alkyl or phenyl, respectively independently substituted with one or more of C1-10alkyl, C1-10alkoxy, phenyl, halogen, CN, and CF3.

4. Composition of any one of claims 2 to 3, wherein B is selected from pyrrole, indole and pyrazole, respectively independently substituted with one or more of C1-10alkyl, C1-10 alkoxy or phenyl.

5. Composition of any one of claims 2 to 4, wherein R2is selected from C1-10 alkyl or phenyl, optionally substituted.

6. Composition of any one of claims 1 to 5, wherein the compound (X) or the compound (X1) and (X2) is / are non-dissociative in the composition at least up to room temperature.

7. Composition of any one of claims 2 to 6, wherein C is an electron-withdrawing group, and 1,10-phenanthroline is unsubstituted; or C is an electron-withdrawing group, and 1,10-phenanthroline is substituted with one or more electron-donating groups; or B is identical to C, wherein C is an electron-withdrawing group, and 1,10- phenanthroline is unsubstituted; or B is identical to C, wherein C is an electron-withdrawing group, and 1,10- phenanthroline is substituted with one or more electron-donating groups; or B is different from C, wherein both B and C are electron-withdrawing groups, and 1,10-phenanthroline is unsubstituted; or B is different from C, wherein both B and C are electron-withdrawing groups, and 1,10-phenanthroline is substituted with one or more electron-donating groups; or B is identical to C, wherein C is an electron-withdrawing group, and 2,2’-bipyridine is unsubstituted; or B is identical to C, wherein C is an electron-withdrawing group, and 2,2’-bipyridine is substituted with one or more electron-donating groups; orB is different from C, wherein both B and C are electron-withdrawing groups, and 2,2’-bipyridine is unsubstituted; or B is different from C, wherein both B and C are electron-withdrawing groups, and 2,2’-bipyridine is substituted with one or more electron-donating groups; preferably wherein B is selected from pyrrole, indole and pyrazole, optionally respectively substituted, and C is selected from O-R2, wherein R2is C1-10 alkyl or aryl, or (C1- 10alkyl)3Si or (aryl)3Si, respectively substituted with one or more of halogen or CF3; and 1,10-phenanthroline is unsubstituted or is 1,10-phenanthroline substituted with one or more selected from C1-5 alkyl, C1-5 alkoxy, -O-(CH2)n-O- (n = 1 or 2), and phenyl; or B is identical to C, wherein C is selected from O-R2, wherein R2is C1-10alkyl or aryl, or (C1-10alkyl)3Si or (aryl)3Si, respectively substituted with one or more of halogen or CF3; and 1,10-phenanthroline is unsubstituted or 1,10-phenanthroline is substituted with one or more selected from C1-5alkyl, C1-5alkoxy, -O-(CH2)n-O- (n = 1 or 2), and phenyl; or B is identical to C, wherein C is selected from O-R2, wherein R2is C1-10 alkyl or aryl, or (C1-10alkyl)3Si or (aryl)3Si, respectively substituted with one or more of halogen or CF3; and 2,2’-bipyridine is unsubstituted or is substituted with one or more selected from C1-5 alkyl, C1-5 alkoxy, or phenyl.

8. Composition of any one of claims 6 or 7, wherein the compound is non- dissociative up to a temperature of 50 °C.

9. Composition of any one of claims 2 to 8, wherein R3and R4are independently H, C1-10 alkyl or aryl, wherein C1-10 alkyl or aryl are independently substituted with one or more of C1-5alkyl, C1-5alkyl substituted with one or more of halogen, C1-5alkoxy, phenyl, halogen; orwherein the molar ratio of compound(s) (Y) comprising one or more compounds each comprising an olefinic double bond to the compound (X) or (X1) of formula I or to the compound (X2) of formula II in a composition which has a temperature of 50 °C or below is greater than 2000 or 4000 or 6000 or 8000 or 10,000 or 20,000 or 30,000 or 40,000 compared to the composition which has the temperature above 50 °C; or wherein the temperature is above 55 °C or above 60 °C or above 70 °C or above 80 °C or above 90 °C or above 100 °C; or wherein the temperature is in a range of from above 50 to 140 °C or above 55 to 130 °C or above 60 to 120 °C.

10. Composition of any of claims 1 to 9, wherein the compound (X) is selected from one of the following compounds 5 to 8:wherein R24= methyl, phenyl; R25, R26= H, methyl, CF3; Z =methyl, iso-propyl, halogen; or is selected from one of the following compounds III to VIor is selected from one of the following compounds:R = Me, Ph; Ar = 2,6-diisopropylphenyl;; or is selected from.

11. The composition of any one of claims 1 to 10, wherein the compound (X) has a stability constant which exceeds a value of 250,000 L*mol-1at 298 K in a solvent, wherein the solvent is the one or more compounds (Y) each comprising an olefinic double bond, and / or wherein the solvent is an inert solvent for the compound (X) and / or (Y), the stability constant being determined as defined in the description.

12. The composition of any one of claims 1 to 11, wherein the stability constant is more than 300,000 L*mol-1or more than 350,000 L*mol-1or more than 400,000 L*mol-1.

13. Method of making a composition as defined in any one of claims 1 to 12, comprising: providing a compound (X) and a compound (Y); heating a mixture of the provided compounds to a temperature above 50 °C; wherein the composition does not contain a Lewis acid selected from one or more of MgCl2, MgBr2, MgI2, MnCl2, MnBr2, MnI2, FeCl3, AlCl3, CuCl2, ZnCl2, ZnBr2, ZnI2, Zn(triflate)2or Zn(trifluoroacetate)2; preferably wherein the composition does not contain an inert solvent for the compound (X) and / or (Y).

14. Method of activating a compound (X) as defined in any one of claims 1 to 12 for initiating an olefinic metathesis reaction in a composition comprising one or more compound(s) (Y) each comprising an olefinic double bond, the method comprising: heating a composition comprising the compounds (X) and (Y) to a temperature above 50 °C; wherein the composition does not contain a Lewis acid selected from one or more of MgCl2, MgBr2, MgI2, MnCl2, MnBr2, MnI2, FeCl3, AlCl3, CuCl2, ZnCl2, ZnBr2, ZnI2, Zn(triflate)2or Zn(trifluoroacetate)2;preferably wherein the composition does not contain an inert solvent for the compound (X) and / or (Y); or method of performing a metathesis reaction, the method comprising: heating a composition comprising a compound (X) and one or more compounds (Y) as defined in any one of claims 1 to 10 to a temperature above 50 °C, wherein the composition does not contain a Lewis acid selected from one or more of MgCl2, MgBr2, MgI2, MnCl2, MnBr2, MnI2, FeCl3, AlCl3, CuCl2, ZnCl2, ZnBr2, ZnI2, Zn(triflate)2 or Zn(trifluoroacetate)2; preferably wherein the composition does not contain an inert solvent for the compound (X) and / or (Y).

15. Composition, comprising: a compound (X) and one or more compounds (Y) as defined in any one of claims 1 to 12; wherein the composition does not contain a Lewis acid selected from one or more of MgCl2, MgBr2, MgI2, MnCl2, MnBr2, MnI2, FeCl3, AlCl3, CuCl2, ZnCl2, ZnBr2, ZnI2, Zn(triflate)2or Zn(trifluoroacetate)2; wherein the composition has a temperature below 50 °C; preferably wherein the composition does not contain an inert solvent for the compound (X) and / or (Y).

16. Use of the composition as defined in claim 15 in a metathesis reaction, the use comprising: heating the composition above a temperature of 50 °C.

17. Use of a compound (X) for initiating a metathesis reaction in a composition comprising one or more compound(s) (Y) as defined in any one of claims 1 to 12, the use comprising: heating a composition comprising the compounds (X) and (Y) to a temperature above 50 °C; wherein the composition does not contain a Lewis acid selected from one or more of MgCl2, MgBr2, MgI2, MnCl2, MnBr2, MnI2, FeCl3, AlCl3, CuCl2, ZnCl2, ZnBr2, ZnI2, Zn(triflate)2 or Zn(trifluoroacetate)2; preferably wherein the composition does not contain an inert solvent for the compound (X) and / or (Y).

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