Diaminotrisphenol compound, its metal complexes and a supported catalyst

Abstract

The invention is directed to a diaminotrisphenol compound according to the following formula: following formula: wherein R1 and R2 are hydrogen or a substituent, R3 is a hydroxyl group, carboxylic acid group, an ester group or a group comprising alkyl(trialkoxy)silane or alkyltrichlorosilane and wherein n is 2 or 3 and m is 2 or higher.

Description

[0001] DIAMINOTRISPHENOL COMPOUND, ITS METAL COMPLEXES AND A SUPPORTED CATALYST

[0002] The invention is directed to a novel diaminotrisphenol ligand, its metal complexes and a supported catalyst comprising the metal complexes.

[0003] Organometallics 2023, 42, 2102-2110 describes diaminotrisphenolate aluminium complexes.

[0004] Organometallics 2023, 42, 2102-2110 describes diaminotrisphenolate aluminium complexes.

[0005] ACS Sustainable Chem. Eng. 2020, 8, 13185-13194 describes diaminotrisphenolate rare earths complexes.

[0006] Chin. J. Chem. 2024, 42, 1571 -1581 describes diaminotrisphenolate rare earths complexes.

[0007] ChemCatChem 2021 , 13, 4099-4110 describes aminotrisphenolate gallium complexes.

[0008] The metal complexes of these known diaminotrisphenol ligands are interesting because they can be used as a catalyst in the preparation of cyclic carbonate compounds starting from carbon dioxide and an epoxide. A problem with the prior art ligands and their corresponding metal complexes is that they are difficult to immobilise to a heterogeneous support. Such supported metal complexes are preferred when used as a catalyst. This because it enables a more simple separation of the catalyst and the reactants of the cyclic carbonate synthesis.

[0009] The object is to provide a ligand which can be simply immobilised on a heterogeneous support.

[0010] This object is achieved with the following diaminotrisphenol ligand. A diaminotrisphenol compound according to the following formula: wherein R1 and R^ are hydrogen or a substituent, RS is a hydroxyl group, carboxylic acid group, an ester group or a group comprising alkyl(trialkoxy) silane or alkyltrichlorosilane and wherein n is 2 or 3 and m is 2 or higher.

[0011] The aliphatic RS group, being a hydroxyl group, carboxylic acid group or an ester group can selectively react with anchoring groups such as 3- isocyanatopropyl(trimethoxyilane) or 3-chloropropyltrimethoxy silane or 3- bromopropyltrimethoxysilane. The thus obtained reaction product is easily immobilised on for example a silica support. When RS is a group comprising alkyl(trialkoxy) silane or alkyltrichlorosilane it may be directly immobilised by covalent bonding to for example a silica support.

[0012] A preferred diaminotrisphenol ligand is where n is 2 or 3, preferably n is 2, to allow for the formation of a 5- or 6-membered metal chelate ring when reacted with a suitable metal compound. The choice for m is less critical as it forms the connection to the heterogeneous support. Good results have been achieved when m is 2 but m may also be higher. Preferably the direct chain of atoms connecting the amine of the ligand and the support contains 6 or less carbon atoms. This direct chain of atoms may further comprise of heteroatoms, such as oxygen, nitrogen and sulphur. Preferably one to three of such heteroatoms are present in this chain.

[0013] R1and R2may be hydrogen or any hydrocarbon substituent or a functional group substituent and more preferably both are a hydrocarbon substituent or a functional group substituent or a combination of a hydrocarbon substituent and a functional group substituent. Examples of hydrocarbon substituents are alkyl groups having 1 to 5 carbon atoms, for example methyl, ethyl, propyl, iso-propyl, butyl, tert-butyl, preferably methyl and tert-butyl. Possible aryl groups are phenyl and methyl-substituted phenyl. The substituent may also be a functional group, for example a nitro (-NO2) group, a halogen like a chloro, bromo or fluoro group, or a methoxy (-OMe) group. Examples of compounds prepared and having a catalytic activity are compounds wherein R1 is methyl, tert-butyl or chloro in combination with a R2 group which is methyl or chloro. Homogeneous experiments show a high catalytic activity when R1 or R2 are chloro or when R1 and R2 are both chloro.

[0014] R2is a hydroxyl group, carboxylic acid group or an ester group. The ester group may be an -C(O)OR4group wherein R4is a hydrocarbon group having from 1 to 5 carbon atoms. Possible groups R4are methyl, ethyl, propyl, iso-propyl, butyl and tert, -butyl. Preferably R4is methyl. R2may also comprise a group comprising alkyl(trialkoxy) silane or alkyltrichlorosilane. Preferably the alkyl group of the alkyl(trialkoxy) silane or alkyltrichlorosilane has 2 to 6 carbon atoms and the alkoxy group of the alkyl(trialkoxy)silane has 1 to 3 carbon atoms.

[0015] The diaminotrisphenol ligand of this invention is not only of interest in that it can be easily immobilised, but additionally, it is also advantageous because it can be prepared in a single synthesis step starting from simple starting compounds. The ligand may be prepared by alkylation of a suitable diamine with optionally substituted phenols containing a 2-bromomethyl group, or by a reductive amination employing a suitable diamine with optionally substituted phenols containing a 2-formyl group, or through a Mannich condensation reaction of a suitable diamine with an optionally substituted phenol and (para)formaldehyde. A Mannich condensation is preferred as it does not require functionalisation of the optionally substituted phenol at the 2-position prior to reaction with the amine. The invention is therefore also directed to this reaction where a functionalised diamine having a group R2reacts with a corresponding optionally substituted phenol and formaldehyde to form the diaminotrisphenol ligand and water as a byproduct. The formaldehyde may be added to the reaction mixture as such or added as a precursor, such as paraformaldehyde, which forms the formaldehyde in situ. A preferred substituted phenol is ortho substituted with a group R1and para substituted with a group R2. The functionalised diamine has a primary amine, a secondary amine and a R2group and a phenylene or preferably an alkylene group bridging the primary amine and the secondary amine and an alkylene group bridging the secondary amine with the R2group. The R2group of the functionalised diamine is a hydroxyl group, carboxylic acid group or an ester group. Examples of suitable diamines are 2-((2-aminoethyl) amino)ethan-1 -ol, 3-((2-aminoethyl)amino)propan-1 -ol, 2-((3- aminopropyl)amino)ethan-1 -ol, 3-((2-aminoethyl)amino)propanoic acid or methyl 3-((2-aminoethyl)amino)propanoate. Examples of suitable substituted phenols are 2,4-di-tert-butylphenol 2,4-dimethylphenol, 2-tert-butyl-4- methylphenol, 2-tert-butyl-4-methoxyphenol, 2-tert-butyl-4-chlorophenol, 4- chloro-2-methylphenol, 2,4-dichlorophenoL It is believed that this reaction proceeds according to a so-called Mannich reaction.

[0016] The reaction is preferably presented as:

[0017] The preparation of the diaminotrisphenol ligand may be performed in a solvent. Preferably the preparation is performed under neat conditions in the absence of a solvent. The reactants are preferably mixed in around stoichiometric quantities. The temperature at which the preparation is performed is suitably below the boiling points of the reactants at the chosen pressure and may be between 65 and 1 10QC and preferably between 85 and 95 °C. The pressure is suitably ambient pressure.

[0018] The diaminotrisphenol ligand may be isolated from the reaction mixture by chromatography, precipitation and / or crystallization.

[0019] The diaminotrisphenol ligand of this invention and the ligand as obtained by the above process may advantageously be combined with a metal to form a complex. Possible metals which can be used are one or more chosen from the group of aluminium, gallium, indium, iron, cobalt, nickel, zinc, titanium and / or bismuth. In addition the metal may be a rare earth metal such as Y, Sm, Nd and La. Preferably the metal is one of Ga, Fe and Al and the metal complex may be advantageously used as a catalyst in the preparation of cyclic carbonates. The complex may be used as a homogeneous catalyst and preferably as a supported catalyst comprising the complex. The invention is for this reason also directed to the complex as such as well as to a supported catalyst comprising the complex.

[0020] Gallium complexes are preferably prepared by contacting a suitable gallium compound with the ligand in a solvent. Suitable gallium compounds may be gallium(lll) ethoxide, gallium(lll) acetylacetonate or gallium(lll) chloride. A suitable solvent is tetrahydrofuran (THF). The reaction may be performed at ambient conditions.

[0021] Aluminium complexes are preferably prepared by contacting a suitable aluminium compound with the ligand in a solvent. Suitable aluminium compounds may be aluminium(lll) isopropoxide, trimethyl aluminium or aluminium(lll) chloride. A suitable solvent is tetrahydrofuran (THF). The reaction may be performed at ambient conditions.

[0022] Iron complexes are preferably prepared by contacting a suitable iron compound with the ligand in a solvent. Suitable iron compounds may be iron(lll) chloride or iron(lll) acetylacetonate. Suitable solvents are tetrahydrofuran (THF), ethyl acetate or methanol. The reaction may be performed at ambient conditions.

[0023] The preferred metal complex may suitable be prepared by first preparing a diaminotrisphenol compound by a process according to this invention to obtain a reaction mixture containing the diaminotrisphenol compound and wherein without isolation of the diaminotrisphenol compound from the reaction mixture a suitable gallium, aluminium or iron compound is added to the reaction mixture to obtain the corresponding metal complex.

[0024] The metal complex of this Invention may be used as a homogeneous catalyst and preferably as a supported catalyst comprising the complex. The invention is thus also directed to a homogeneously catalysed process to prepare a cyclic carbonate by reacting an epoxide compound and carbon dioxide in the presence of the metal complex and a quaternary ammonium halogen salt or a quaternary phosphonium halogen salt. These salts may be those described below, except that in this process they are dissolved in the reaction medium. Preferably the metal complex is part of a supported catalyst as described below because this avoids the use of dissolved quaternary ammonium halogen salt or a quaternary phosphonium halogen salt.

[0025] The supported catalyst will comprise a solid support. Preferably the complex is covalently bonded to the surface of the solid support. For covalent binding, the solid support needs to contain or be derivatized to contain reactive functionalities which can serve for covalently linking an anchoring compound to the surface thereof. Examples of suitable reactive functionalities are titanol (Ti-OH), silanol (Si-OH) and aluminol (AI-OH). Materials having such functionalities are for example silicon dioxide supports containing reactive silanol groups, alumina supports containing reactive aluminol groups, amorphous silica-alumina supports having both silanol and aluminol groups and sol-gel materials. Other possible carrier particles may be polyacrylamide supports, polystyrene supports and polyethylene glycol supports.

[0026] Preferred solid supports are titanium dioxide, silica, alumina and / or silica alumina as present as particles. The silanol groups as present on the surface of the silica or silica-alumina particle and / or the aluminol groups as present on the surface of the alumina or silica-alumina particle or the titanol as present on the surface of the titanium dioxide particle are covalently connected to the complex by an anchoring group.

[0027] The catalyst particle may be relatively large when used as part of a packed bed in a reactor. In such a bed inert particles may also be present. The supported catalyst may also be present as a suspension in a liquid reaction mixture. The support will then be present as a powder having dimensions which are small enough to create a high active catalytic surface per weight of the support and large enough to be easily separated from the cyclic carbonate in or external of the reactor. Preferably the support powder particles have for at least 90 wt% of the total particles a particle size of above 10 pm and below 2000 pm. The particle size is measured by a Malvern® Mastersizer® 2000.

[0028] The anchoring group is connected to the hydroxyl group of the ligand. Preferably a bi functional compound having a functional group which can react with the hydroxyl group of the ligand and provided with a functional group which can covalently bond with the surface of a solid support is reacted with the ligand or more preferably with the metal complex comprising the ligand.

[0029] Suitable functional groups which can react with the hydroxyl group R^ are chloro groups, bromo groups and isocyanato groups. Suitable functional groups which can react with the carboxylic acid group or ester RS are amino groups.

[0030] Suitable functional groups which can covalently bond with the surface of a solid support are alkyl(trialkoxy) silane wherein the alkyl group preferably has 2 to 6 carbon atoms and the alkoxy group has preferably 1 to 3 carbon atoms, and alkyltrichlorosilane wherein the alkyl group preferably has 2 to 6 carbon atoms.

[0031] The functional groups which can react with the hydroxyl group and the functional groups which can covalently bond with the surface of a solid support are preferably present at either end of an alkylene group having between 2 and 10 carbon atoms, preferably between 3 and 6 and most preferably 4 carbon atoms, for example 3 carbon atoms Examples of suitable compounds which are reacted and connected to the hydroxyl group R^ of the ligand are (3-isocyanatopropyl)trimethoxysilane, (4-isocyanatobutyl)trimethoxysilane, (3-chloropropyl)trimethoxysilane, and (3- bromopropyl)trimethoxysilane

[0032] Examples of suitable compounds which are reacted and connected to the carboxylic acid group or ester group R^ of the ligand are 3- aminopropyl(trimethoxysilane), and 4-aminobutyl(trimethoxysilane).

[0033] The reaction product of ligands or metal complexes comprising the ligand and the bi functional compound are subsequently immobilised on a solid support. In a preferred embodiment the preferred trialkoxy groups react with the silanol, titanol or aluminol groups of the solid support to obtain the supported catalyst.

[0034] The heterogeneous or supported catalyst comprises carrier particles having a carrier surface, to which carrier surface the metal-complex is immobilised. Preferably also a halogen salt is immobilised such that the metal-complex and the halogen salt are each individually immobilised to the carrier surface. Applicants have found that this supported catalyst can be advantageously be used as a catalyst or as part of a catalyst in a chemical process in the presence of an organic halogen compound and in the absence of a non-immobilised halogen ammonium salt. The presence of this halogen compound enhances the activity of the catalyst and enhances the activity when the catalyst is reused in for example subsequent batch or semi-batch operations to prepare the cyclic carbonate. This allows one to use this catalyst in chemical processes which are up to now catalysed by metal complexes and in the presence of a non-immobilised halogen ammonium salt. By using this catalyst in the presence of an organic halogen compound one does not require the presence of the unwanted non-immobilised halogen ammonium salt. It is especially found that this supported catalyst can be used in a process to prepare a cyclic carbonate by reacting an epoxide compound and carbon dioxide without leaching of a halogen ammonium salt.

[0035] The halogen salt is preferably an ammonium or phosphonium halogen salt. The choice of the halogen will also decide the choice of any other halogen compound used as part of the catalyst system as they are preferably the same. This halogen is also referred to as the catalyst system halogen. Preferred halogen salts are iodide salts and bromide salts. The iodide salt which is immobilised is preferably a quaternary phosphonium iodide salt and more preferably a quaternary ammonium iodide salt. The bromide salt which is immobilised is preferably a quaternary phosphonium bromide salt and more preferably a quaternary ammonium bromide salt.

[0036] The immobilised halogen salt is preferably a quaternary ammonium halogen salt or a phosphonium salt having the following general formula R5R6R7R8ZX, wherein X is an iodide anion and preferably a bromide, Z may be N or P, R5 is an anchoring group which covalently binds the quaternary ammonium halogen salt or quaternary phosphonium halogen salt to the carrier surface and R® , R7and R^ are the same or different alkyl groups having between 1 and 20 carbon atoms. The anchoring group preferably comprises a functional group which can covalently bond with the surface of a solid support such as described above for immobilising the ligand or the complex. These functional groups are preferably alkyl(trialkoxy) silane wherein the alkyl group preferably has 2 to 6 carbon atoms and the alkoxy group has preferably 1 to 3 carbon atoms and alkyltrichlorosilane wherein the alkyl group preferably has 2 to 6 carbon atoms.

[0037] Furthermore, the fact that the metal-complex and the halogen salt are each individually immobilised enables one to influence the relative presence of the halogen salt with respect to the metal complex in the catalyst. It has been found that after immobilisation also immobilised amine is found on the carrier surface. It is believed that part of the halogen salt converts to an amine by means of the reversed Menshutkin reaction as illustrated below in more detail.

[0038] An amine may also be individually immobilised to the carrier surface next to the metal complex. Preferably an amine is individually immobilised to the carrier surface next to the metal complex and the halogen salt, although good results are achieved when no amine is immobilised next to the metal complex and the halogen salt. The amine may be a tertiary amine. The tertiary amine may be presented as R9R10R11 N and wherein R9 is an anchoring group which covalently binds the tertiary amine to the carrier surface and R^ 0 and R^ 1 are the same or different alkyl group having from 1 to 20 carbon atoms or wherein R10 and R1 1are part of a ring structure forming a 5- or 6 membered ring or R10 or R11 are amino alkyl groups. The anchoring group R^ preferably comprises a functional group which can covalently bond with the surface of a solid support such as described above for immobilising the ligand or the complex. These functional groups are preferably alkyl(trialkoxy) silane wherein the alkyl group preferably has 2 to 6 carbon atoms and the alkoxy group has preferably 1 to 3 carbon atoms and alkyltrichlorosilane wherein the alkyl group preferably has 2 to 6 carbon atoms.

[0039] The molar ratio of the separately immobilised halogen salt and the metal complex is preferably higher than 2:1 , more preferably higher than 3:1 and below 10:1 . The molar ratio between the separately immobilised amine and the metal complex is preferably between 0:1 and 10:1 and more preferably between 0:1 and 5:1 .

[0040] The metal-complex, the halogen salt and the optional tertiary amine are thus suitably individually immobilised to the carrier surface of the heterogeneous catalyst as presented below:

[0041] S-(R9-(R10R1 1Z))k

[0042] S- (R5 -(R5R7R8NX))mS-(R1 2-MetalComplex)nwherein S is the carrier surface, Z may be N or P, and R$- R^ are as above. R9 and R^2are the anchoring group which covalently binds the metal complex to the carrier surface S and wherein k:m:n is the molar ratio of the amine, the halogen salt and the metal-complex as individually immobilised to the carrier surface S.

[0043] When a halogen salt, such as a bromide salt, is immobilised, preferably a halogen compound, such as a bromide compound, is present in a liquid and / or gaseous reaction mixture as the corresponding halogen compound. This halogen compound is thus non-immobilised. Without wishing to be limited by the following theory but applicants believe that the halogen compound can in-situ repair any deactivated immobilised halogen salt by reaction of the halogen compound with immobilised amine compound. This is illustrated below for 1 ,4 dibromobutane as the bromide compound and for an illustrative individually immobilised bromide salt and an illustrative individually immobilised tertiary amine compound.

[0044] reverse Menshutkin reaction reverse Menshutkin reaction

[0045] R = methyl, butyl R = methyl, butyl R = methyl, butyl

[0046] The above equilibrium reactions, also known as the Menshutkin reaction and the reversed Menshutkin reaction, shows that the immobilised bromide salt and the immobilised tertiary amine are in an equilibrium in the presence of the non-immobilised halogen compound. Preferably a fresh catalyst is at least immobilised with the halogen salt because this will also result in that immobilised tertiary amine compounds are formed on the carrier surface. The tertiary amine compound may also be individually immobilised. The catalyst will, in use, in a process to prepare a cyclic carbonate by reacting an epoxide compound and carbon dioxide in the presence of a halogen compound be enriched in immobilised amine halogen salt compounds. This as a result of the Menshutkin reaction between the halogen compound and the immobilised tertiary amine compound.

[0047] When the desired bromide salt is immobilised the process is preferably performed in the presence of an aryl bromide and / or an alkyl bromide. Thus, re-activation with a tetra-n-butylammonium bromide (TBAB) as in the process of W02009 / 109765 can be omitted. A suitable aryl bromide is benzyl bromide. Because benzyl bromide is corrosive for some metals it may be preferred to perform the process in glass or glass lined process apparatuses. Preferably less corrosive bromide compounds are used such as alkyl bromide, such as C3-C10 alkyl bromide compounds, for example propyl bromide, butyl bromide, pentyl bromide, hexyl bromide, heptyl bromide and octyl bromide. Another suited group of alkyl bromides are alkyl dibromides, such as 1 ,2-dibromoethane, 1 ,3-dibromopropane, 1 ,4-dibromobutane, 1 ,5 dibromopentane and 1 ,6-dibromohexane.

[0048] The starting epoxide compound suitably has 2 to 8 carbon atoms. Suitable epoxide compounds are ethylene oxide, propylene oxide, butylene oxide, pentene oxide, glycidol, styrene oxide, epichlorohydrin or fluoroethylene oxide.

[0049] The process may be performed as a continuous process wherein the heterogeneous catalyst is present as part of a fixed bed in a fixed bed reactor. The halogen compound may then be co-fed to the fixed bed reactor together with the epoxide and carbon dioxide. Depending on the epoxide and further process conditions the reaction in the fixed bed may be performed in the gas or liquid phase or combinations of gas and liquid phases. The temperature may be between 20 and 150 °C, more preferably between 40 and 120 °C, and the absolute pressure is suitably between 0.1 and 0.5 mPa, more preferably between 0.1 and 0.3 mPa.

[0050] The carbon dioxide is suitably contacted with the epoxide compound in a suspension of liquid cyclic carbonate and the heterogeneous catalyst. The temperature and pressure conditions are chosen such that the cyclic carbonate is in its liquid state. The temperature and pressure conditions are further chosen such that carbon dioxide and epoxide easily dissolve in the liquid cyclic carbonate reaction medium. The temperature may be between 0 and 200 °C and the pressure between 0 and 5.0 mPa (absolute) and wherein temperature is below the boiling temperature of the cyclic carbonate product at the chosen pressure. At the high end of these temperature and pressure ranges complex reactor vessels will be required. Because favourable results with respect to selectivity and yield to the desired carbonate product are achievable at lower temperatures and pressures it is preferred that the temperature is between 20 and 150 °C, more preferably between 40 and 120 °C, and the absolute pressure is between 0.1 and 0.5 mPa, more preferably between 0.1 and 0.4 mPa. The process may be performed as for example described in WO2021 / 094447.

[0051] Example 1 (Compound A-1 )

[0052] In this example the process to prepare the ligand to the below scheme is described.

[0053] Paraformaldehyde Neat, 90 °C, 64 hours

[0054] To a 100 mL round bottom, 2,4-dimethylphenol (7.58 g, 62.0 mmol, 3.1 equiv.), paraformaldehyde (1 .80 g, 60.0 mmol, 3.0 equiv.) and 2-((2- aminoethyl)amino)ethan-1 -ol (2.08 g, 20.0 mmol, 1.0 equiv.) were added. The reaction was heated to 90 °C resulting in a light-yellow solution and was allowed to proceed at this temperature for 64 hours leaving the reaction mixture unchanged. Afterwards, the reaction mixture was cooled to room temperature and dissolved as a slightly yellow solution in diethyl ether (25 mL). To this solution, a generous amount of sodium sulfate was added which was subsequently filtered off and washed with di-ethyl ether (2 x 5 mL). To the slightly yellow filtrate, pentane (75 mL) was added leaving the reaction mixture unchanged. This solution was cooled to -20 °C for 40 hours resulting in a white precipitate in a slightly yellow solution. This suspension was filtered and washed with ice-cold diethyl ether / pentane (1 :1 , 2 times 20 mL) resulting in a white residue and a slightly yellow filtrate. The residue was dried under reduced pressure at room temperature for 2 hours. The desired product was isolated as a white powder (5.47 g, 54.0 %).

[0055] Alternatively, the product can be purified directly after the reaction by column chromatography on silica by eluting with heptane / ethyl acetate / triethylamine (80:20:2) until a yellow band comes off followed by eluting with heptane:isopropanol:triethyl amine (90:10:2).

[0056] 1H NMR (300 MHz, DMSO-cfe): 5 6.78 (s, 3H, Ar-H), 6.69 (s, 2H, Ar-H), 6.56 (s, 1 H, Ar-H), 3.59 (s, 6H, Ar-CH2), 3.48 (s, 2H, CH2OH), 2.68 (s, 2H, CH2), 2.60 (s, 2H, CH2), 2.48 (s, 2H, CH2CH2OH), 2.14 (s, 9H, ArCH3), 2.09 (s, 6H, ArCH3), 2.02 (s, 3H, ArCH3).

[0057] 13C NMR (75 MHz, DMSO-cfe): 5 153.01 , 152.24, 130.36, 129.94, 127.93, 126.97, 126.71 , 126.40, 123.89, 123.42, 122.49, 121.40, 58.12, 57.11 , 55.25, 54.92, 49.56, 48.79, 20.13, 16.17, 15.58.

[0058] Example 2 (compound A-1 )

[0059] In this example the process to prepare compound A-1 of Example 1 on a ten-fold scale using toluene as a reaction medium is described. Paraformaldehyde

[0060] 3 toluene, 90 °C, 48 hours

[0061] To a 500 mL round bottom, 2-((2-aminoethyl)amino)ethan-1 -ol (20.83 g, 200 mmol, 1 .0 equiv.), paraformaldehyde (18.03 g, 600 mmol, 3.0 equiv.), 2,4-dimethylphenol (75 mL, 620 mmol, 3.1 equiv.) and 25 mL toluene were added. A reflux condenser was added on top of the flask. The reaction was heated to 90 °C resulting in a light-yellow solution and was allowed to proceed at this temperature for 48 hours under gentle stirring.

[0062] Afterwards, the reaction mixture was cooled to room temperature, resulting in the formation of and aqueous layer on top of a viscous yellow liquid. The aqueous layer was decanted, after which the reaction mixture was diluted with 125 mL toluene. To this solution, a total of 350 mL pentane was added slowly, resulting in the formation of a voluminous precipitate. This suspension was filtered and washed twice with 350 mL of 20% toluene in pentane (v / v), resulting in a white residue and a slightly yellow filtrate. The residue was subsequently washed with 350 and 200 mL pentane, resulting in a white residue and a clear filtrate.

[0063] The residue was dried under reduced pressure at room temperature for 3 hours. The desired product was isolated as a white powder (78.67 g, 77.6 %).

[0064] Example 3 (compound A-2)

[0065] In this example the process to prepare the compound to the below scheme is described.

[0066] Paraformaldehyde

[0067] Neat, 90 °C, 72 hours

[0068] To a 100 mL round bottom, 2-tert-butyl-4-methylphenol (10.18 g, 62.0 mmol, 3.1 equiv.), paraformaldehyde (1.80 g, 60.0 mmol, 3.0 equiv.) and 2- ((2-aminoethyl)amino)ethan-1 -ol (2.08 g, 20.0 mmol, 1.0 equiv.) were added. The reaction was heated to 90 °C resulting in a light-yellow solution and was allowed to proceed at this temperature for 72 hours leaving the reaction mixture unchanged. Afterwards, the reaction mixture was cooled to room temperature and dissolved as a slightly yellow solution in diethyl ether (50 mL). To this solution, a generous amount of sodium sulfate was added which was subsequently filtered off and washed with diethyl ether (2 x 20 mL). To the filtrate were added 3 mL ethyl acetate and 2 mL toluene, and the solution was concentrated in volume on the rotary evaporator. The resulting liquid was purified by column chromatography on silica by eluting using a gradient from heptane I ethyl acetate I toluene I triethylamine 85 : 5 : 10 : 1 (v / v / v / v) to heptane I ethyl acetate I toluene I triethylamine 65 : 30 : 10 : 1 (v / v / v / v). The product was obtained as a white powder (8.51 g, 67.2%).

[0069] The product was characterised by1H NMR:1H NMR (400 MHz, CDCh): 5 7.01 (s, 2H), 6.98 (s, 1 H), 6.71 (s, 2H), 6.60 (s, 1 H), 3.73 - 3.58 (m, 8H), 2.76 (s, 4H), 2.58 (s, 2H), 2.23 (s, 9H), 1.40 (s, 18H), 1.34 (s, 9H). The NMR data indicates that the desired product was formed.

[0070] Example 4 (compound A-3)

[0071] In this example the process to prepare the compound to the below scheme is described.

[0072] To a 100 mL round bottom, 4-chloro-2-methylphenol (8.84 g, 62.0 mmol, 3.1 equiv.), paraformaldehyde (1.80 g, 60.0 mmol, 3.0 equiv.) and 2- ((2-aminoethyl)amino)ethan-1 -ol (2.08 g, 20.0 mmol, 1.0 equiv.) were added. The reaction was heated to 90 °C resulting in a light-purple solution and was allowed to proceed at this temperature for 72 hours leaving the reaction mixture unchanged. Afterwards, the reaction mixture was cooled to room temperature and dissolved as a dark red to purple solution in diethyl ether (50 mL). To this solution, a generous amount of sodium sulfate was added which was subsequently filtered off and washed with diethyl ether (2 x 20 mL). To the filtrate were added 3 mL ethyl acetate and 2 mL toluene, and the solution was concentrated in volume on the rotary evaporator. The resulting liquid was purified by column chromatography on silica by eluting using a gradient from heptane / ethyl acetate / toluene / triethylamine 60 : 30 : 10 : 1 (v / v / v / v) to heptane I ethyl acetate I toluene I triethylamine 20 : 70 : 10 : 1 (v / v / v / v). The desired product was obtained as a white powder (4.22 g, 37.2%).

[0073] The product was characterised by1H NMR:1H NMR (400 MHz, CDCh): 5 7.06 (s, 2H), 7.03 (s, 1 H), 6.87 (s, 2H), 6.80 (s, 1 H), 3.79 (t, J = 4.7 Hz, 2H), 3.70 (s, 2H), 3.64 (s, 4H), 2.84 - 2.78 (m, 2H), 2.77 - 2.71 (m, 2H), 2.61 (t, J = 5.0 Hz, 2H), 2.22 (s, 6H), 2.15 (s, 3H). The NMR data indicates that the desired product was formed.

[0074] Example 5 (compound A-4)

[0075] In this example the process to prepare the compound to the below scheme is described.

[0076] To a 100 mL round bottom, 2,4-dimethylphenol (7.58 g, 62.0 mmol, 3.1 equiv.), paraformaldehyde (1 .80 g, 60.0 mmol, 3.0 equiv.) and 3-((2- aminoethyl)amino)propan-1 -ol (2.36 g, 20.0 mmol, 1.0 equiv.) were added. The reaction was heated to 90 °C resulting in a light-yellow solution and was allowed to proceed at this temperature for 72 hours leaving the reaction mixture unchanged. Afterwards, the reaction mixture was cooled to room temperature and dissolved as a slightly yellow solution in diethyl ether (50 mL). To this solution, a generous amount of sodium sulfate was added which was subsequently filtered off and washed with diethyl ether (2 x 20 mL). To the filtrate were added 3 mL ethyl acetate and 2 mL toluene, and the solution was concentrated in volume on the rotary evaporator. The resulting liquid was purified by column chromatography on silica by eluting using a gradient from heptane / ethyl acetate / toluene / triethylamine 70 : 20 : 10 : 1 (v / v / v / v) to heptane I ethyl acetate I toluene I triethylamine 30 : 60 : 10 : 1 (v / v / v / v).

[0077] The desired product was obtained as a yellowish powder (5.14 g, 49.4%).

[0078] The product was characterised by1H NMR:1H NMR (400 MHz, CDCh): 5 6.86 (s, 2H), 6.84 (s, 1 H), 6.69 (s, 2H), 6.56 (s, 1 H), 3.67 (s, 4H), 3.62 (s, 2H) 3.55 (d, J = 2.0 Hz, 2H), 2.75 (s, 4H), 2.55 (t, J = 6.0 Hz), 2.24 - 2.15 (m, 18H), 1 .72 - 1 .62 (m, 2H). The NMR data indicates that the desired product was formed.

[0079] Example 6 (compound A-5)

[0080] In this example the process to prepare the compound to the below scheme is described.

[0081] To a 100 mL round bottom, 2,4-dimethylphenol (7.58 g, 62.0 mmol, 3.1 equiv.), paraformaldehyde (1 .80 g, 60.0 mmol, 3.0 equiv.) and 2-((3- aminopropyl)amino)ethan-1 -ol (2.36 g, 20.0 mmol, 1.0 equiv.) were added. The reaction was heated to 90 °C resulting in a light-yellow solution and was allowed to proceed at this temperature for 72 hours leaving the reaction mixture unchanged. Afterwards, the reaction mixture was cooled to room temperature and dissolved as a slightly yellow solution in diethyl ether (50 mL). To this solution, a generous amount of sodium sulfate was added which was subsequently filtered off and washed with diethyl ether (2 x 20 mL). To the filtrate were added 3 mL ethyl acetate and 2 mL toluene, and the solution was concentrated in volume on the rotary evaporator. The resulting liquid was purified by column chromatography on silica by eluting using a gradient from heptane I ethyl acetate I toluene I triethylamine 70 : 20 : 10 : 1 (v / v / v / v) to heptane / ethyl acetate / toluene / triethylamine 30 : 60 : 10 : 1 (v / v / v / v). The desired product was obtained as a yellowish powder (7.17 g, 68.8%).

[0082] The product was characterised by1H NMR:1H NMR (400 MHz, CDCh): 5 6.86 (s, 3H), 6.71 (s, 2H), 6.60 (s, 1 H), 3.74 - 3.65 (m, 8H), 2.67 - 2.61 (m, 2H), 2.59 - 2.50 (m, 4H), 2.24 - 2.16 (m, 18H), 1 .91 - 1 .81 (m, 2H). The NMR data indicates that the desired product was formed.

[0083] Example 7 (Compound B-1 )

[0084] The preparation of a [Ga(diaminotrisphenolate)] complex according to the below scheme is described.

[0085] To a 250 mL round bottom Schlenk flask, the diaminotrisphenol ligand of Example 1 (4.96 g, 9.79 mmol, 1 .0 equiv.), gallium(lll) ethoxide (2.01 g, 9.79 mmol, 1 .0 equiv.) and pre-dried THF (100 mL) were added resulting in a slightly turbid light yellow solution. The reaction was allowed to proceed at room temperature for 16 hours. The reaction mixture was then filtered over Celite filter aid and washed with THF (2 x 15 mL) resulting in a clear slightly yellow solution as the filtrate. Afterwards, the THF was evaporated off under reduced pressure and further dried under reduced pressure at room temperature for 2 hours. The Ga(diaminotrisphenolate) complex was isolated as the THF-adduct being an off-white powder (6.30 g, 99.7 %).

[0086] 1H NMR (300 MHz, DMSO-cfe) 5 7.19 (s, 1 H, OH), 6.88 - 6.73 (m, 3H, Ar-H), 6.61 (d, J = 2.2 Hz, 1 H, Ar-H), 6.56 (d, J = 2.2 Hz, 1 H, Ar-H), 6.48 (d, J = 2.2 Hz, 1 H, Ar-H), 4.34 (d, J = 12.8 Hz, 1 H, CH2), 4.16 (d, J = 13.4 Hz, 1 H, CH2), 3.89 (d, J = 12.8 Hz, 1 H, CH2), 3.62 (m, 2H, THF, CH2O), 3.58 - 3.31 (m, 6H, Ar-CH2)), 3.02 - 2.84 (m, 2H, CH2), 2.84 - 2.60 (m, 3H CH2), 2.20 (s, 3H, ArCH3), 2.14 (t, J = 5.7 Hz, 12H, ArCH3), 1 .83 (s, 3H, ArCH3), 1 .76 (m, 2H, THF, CH2).

[0087] 13C NMR (75 MHz, DMSO) 5 159.50, 157.87, 130.97, 130.75, 130.46, 127.80, 127.37, 127.10, 126.66, 126.44, 126.17, 123.49, 123.09, 121.96, 121 .55, 120.69, 118.08, 67.06 (THF, CH2O), 61 .33, 59.50, 55.70, 53.82, 53.26, 52.19, 25.18 (THF, CH2), 20.15, 16.93, 16.40, 15.92.

[0088] Example 8 (compound B-2)

[0089] The preparation of a [Al(diaminotrisphenolate)] complex according to the below scheme is described.

[0090] To a 500 mL round bottom, the diaminotrisphenol ligand (10.13 g, 20.0 mmol, 1 .0 equiv.) of Example 1 and THF (200 mL) were added. Upon stirring the ligand dissolved, and after 2 minutes AICIs (2.67 g, 20.0 mmol, 1 .0 equiv.) was added. After 5 minutes of stirring, during which all AICIs dissolved, the addition of triethyl amine (NEt3) (1 1 .2 mL, 80.0 mmol, 4.0 equiv.) resulted in the immediate formation of a white precipitate. The reaction was allowed to proceed at room temperature for 16 hours. The reaction mixture was then filtered over Celite filter aid and washed with THF (2 x 30 mL) resulting in a clear slightly pink solution as the filtrate. Afterwards, the filtrate volume was reduced to approximately 60 mL under reduced pressure. Addition of diethyl ether (240 mL) under stirring resulted in the formation of a white precipitate. This suspension was filtered and washed using diethyl ether (2 x 30 mL) resulting in a white residue and a clear filtrate. The residue was air-dried on the filter for 2 hours, and further dried under reduced pressure at 40 °C for 6 hours. The Al(diaminotrisphenolate) complex was isolated as a white powder (7.04 g, 66.3 %).

[0091] 1H NMR (400 MHz, DMSO-cfe) 5 8.99 (br s, 1 H, OH), 6.80-6.65 (m, 3 H, Ar-H), 6.58-6.48 (m, 2 H, Ar-H), 6.44 (s, 1 H, Ar-H), 4.33 (d, J = 13.2 Hz, 1 H, Ar-CH2), 4.03 (d, J = 13.0 Hz, 1 H, Ar-CH2), 3.91 (d, J = 12.9 Hz, 1 H, Ar-CH2), 3.59-3.43 (m, 1 H, CH2), 3.44 - 3.32 (m, 3H, Ar-CH2and CH2), 3.14-2.99 (m, 2H, Ar-CH2and CH2), 2.88-2.70 (m, 2H, CH2), 2.71 - 2.62 (m, 1 H, CH2), 2.49-2.44 (m, 1 H, CH2), 2.40-2.25 (m, 1 H, CH2), 2.20 - 2.02 (m, 15H, ArCH3), 1.74 (s, 3H, ArCH3).

[0092] 13C NMR (101 MHz, DMSO-cfe) 5 158.67, 157.24, 156.60, 130.63, 130.10, 126.81 , 126.51 , 126.00, 125.92, 124.60, 122.96, 122.04, 121.58, 120.84, 120.66, 119.47, 64.25, 62.45, 60.60, 56.87, 54.36, 53.61 , 20.17, 16.88, 16.58, 15.69.

[0093] Example 9 (compound B-3)

[0094] The preparation of a [Fe(diaminotrisphenolate)] complex according to the below scheme is described.

[0095] To a 250 mL round bottom, the diaminotrisphenol ligand (5.07 g, 10.0 mmol, 1.0 equiv.) of Example 1 and MeOH (100 mL) were added resulting in a white suspension. During stirring, tris(acetylacetonato) iron(lll) (Fe(acac)3) (3.53 g, 10.0 mmol, 1 .0 equiv.) was added, resulting in a strong darkening of the reaction mixture. The reaction was allowed to proceed at room temperature for 16 hours. The reaction mixture was then filtered over Celite filter aid, resulting in the deposition of a dark powder on top of the filter. This material was washed with MeOH until the washings turned from brown to red-violet (approximately 40 mL MeOH). Subsequently, the material was extracted using THF (approximately 80 mL). Afterwards, the solvent of the purple coloured filtrate was evaporated off under reduced pressure and the material further dried under reduced pressure at room temperature for 2 hours. The Fe(diaminotrisphenolate) complex was isolated as the THF- adduct as dark purple powder (3.80 g, 60.0 %).

[0096] Elemental analysis: calcd. for Css^yFelXLOs: C 66.56, H 7.50, N 4.44; found: C 66.26, H 7.53, N 4.42.

[0097] Example 10 (compound B-4)

[0098] The preparation of a [Fe(diaminotrisphenolate)] complex according to the below scheme is described.

[0099] To a 500 mL round bottom, the diaminotrisphenol ligand (10.13 g, 20.0 mmol, 1 .0 equiv.) of Example 1 and MeOH (200 mL) were added resulting in a white suspension. During stirring, Fe(acac)3 (7.06 g, 20.0 mmol, 1 .0 equiv.) was added, resulting in a strong darkening of the reaction mixture. The reaction was allowed to proceed at room temperature for 16 hours. The dark suspension was filtered, and the material on the filter washed with MeOH (2 x 30 mL), resulting in a red-violet residue and a brown filtrate. The residue was air-dried on the filter for 2 hours, and further dried under reduced pressure at room temperature for 2 hours. The Fe(diaminotrisphenolate) complex was isolated as a red-violet powder (7.12 g, 63.6 %).

[0100] Elemental analysis: calcd. for CaiHagFeIX C : C 66.55, H 7.03, N 5.01 ; found: C 66.16, H 6.99, N 4.92. Example 1 1 (compound B-4)

[0101] In this example the process to prepare compound B-4 of Example 10 on a ten-fold scale is described.

[0102] To a 2.5 L round bottom, the diaminotrisphenol ligand (101 .34 g, 200 mmol, 1 .0 equiv.) of Example 2 and MeOH (2.0 L) were added resulting in a white suspension. During stirring, Fe(acac)3 (706.34 g, 200 mmol, 1 .0 equiv.) was added portion-wise over 10-15 minutes, resulting in a strong darkening of the reaction mixture. The reaction was allowed to proceed at room temperature for 16 hours. The dark suspension was filtered, and the material on the filter washed with MeOH (2 x 300 mL), resulting in a red-violet residue and a brown filtrate. The residue was air-dried on the filter for 2 hours, and further dried under reduced pressure at 40 °C for 16 hours. The Fe(diaminotrisphenolate) complex was isolated as a red-violet powder (72.18 g, 64.5 %).

[0103] Example 12 (compound B-5)

[0104] The preparation of a [Fe(diaminotrisphenolate)] complex according to the below scheme is described. To a 250 mL round bottom, the diaminotrisphenol ligand (6.32 g, 10.0 mmol, 1 .0 equiv.) of Example 3 and MeOH (100 mL) were added resulting in clear solution. During stirring, Fe(acac)3 (3.53 g, 10.0 mmol, 1 .0 equiv.) was added, resulting in a strong darkening of the reaction mixture. The reaction was allowed to proceed at room temperature for 16 hours. The dark suspension was filtered, and the material on the filter washed with MeOH (2 x 20 mL), resulting in a dark violet residue and a brown filtrate. The residue was air-dried on the filter for 2 hours, and further dried under reduced pressure at room temperature for 2 hours. The Fe(diaminotrisphenolate) complex was isolated as a dark violet powder (2.02 g, 29.5 %).

[0105] Elemental analysis: calcd. for C4oH5?FeN204: C 70.06, H 8.38, N 4.09; found: C 69.99, H 8.34, N 4.02.

[0106] Example 13 (compound B-6)

[0107] The preparation of a [Fe(diaminotrisphenolate)] complex according to the below scheme is described.

[0108] To a 250 mL round bottom, the diaminotrisphenol ligand (5.67 g, 10.0 mmol, 1 .0 equiv.) of Example 4 and MeOH (100 mL) were added resulting in clear solution. During stirring, Fe(acac)3 (3.53 g, 10.0 mmol, 1 .0 equiv.) was added, resulting in a strong darkening of the reaction mixture. The reaction was allowed to proceed at room temperature for 16 hours. The dark suspension was filtered, and the material on the filter washed with MeOH (2 x 20 mL), resulting in a violet residue and a brown filtrate. The residue was airdried on the filter for 2 hours, and further dried under reduced pressure at room temperature for 2 hours. The Fe(diaminotrisphenolate) complex was 1 isolated as a violet powder (4.50 g, 72.5 %).

[0109] Elemental analysis: calcd. for C28H3oCl3FeN204: C 54.18, H 4.87, N 4.51 ; found: C 54.14, H 4.86, N 4.50.

[0110] Example 14 (compound B-4)The preparation of compound B-4 of Example 10 in a one pot, two step procedure according to the below scheme is described. This procedure allows for the preparation of a [Fe(diamonotrisphenolate)] complex without isolation of the ligand from the reaction mixture.

[0111] To a 250 mL round bottom, 2,4-dimethylphenol (7.58 g, 62.0 mmol, 3.26 equiv.), paraformaldehyde (1.80 g, 60.0 mmol, 3.16 equiv.), 2-((2- aminoethyl)amino)ethan-1 -ol (2.08 g, 20.0 mmol, 1.05 equiv.) and a big egg- shaped stirring bar were added. The reaction was heated to 90 °C resulting in a light-yellow solution and was allowed to proceed at this temperature for 72 hours. Afterwards, the reaction mixture was cooled to room temperature and dissolved using methanol (200 mL). To this solution, Fe(acac)3 (6.71 g, 19.0 mmol, 1 .0 equiv.) was added, resulting in a strong darkening of the reaction mixture. The reaction was allowed to proceed at room temperature for 16 hours. The dark suspension was filtered, and the material on the filter washed with MeOH (2 x 30 mL), resulting in a red-violet residue and a brown filtrate. The residue was air-dried on the filter for 2 hours, and further dried under reduced pressure at room temperature for 2 hours. The Fe(diaminotrisphenolate) complex was isolated as a red-violet powder (6.06 g, 57.0 %).

[0112] Elemental analysis: calcd. for CaiHagFeIX C : C 66.55, H 7.03, N 5.01 ; found: C 66.21 , H 6.99, N 4.95.

[0113] HR-MS (FIA-ESI, m / z): calcd. for C3iH39FeN2O4+H = 560.2332; obtained = 560.2322 [M+H]+. calcd. for C3iH39FeN2O4+Na = 582.2152; obtained = 582.2143 [M+Na]+.

[0114] Example 15 (compound B-6)

[0115] The preparation of compound B-6 of Example 13 in a one pot, two step procedure according to the below scheme is described. This procedure allows for the preparation of a [Fe(diamonotrisphenolate)] complex without isolation of the ligand from the reaction mixture. paraformaldehyde

[0116] Neat, 90 °C, 72 h

[0117] To a 250 mL round bottom, 4-chloro-2-methylphenol (8.84 g, 62.0 mmol, 3.26 equiv.), paraformaldehyde (1.80 g, 60.0 mmol, 3.16 equiv.), 2-((2- aminoethyl)amino)ethan-1 -ol (2.08 g, 20.0 mmol, 1.05 equiv.) and a big egg- shaped stirring bar were added. The reaction was heated to 90 °C resulting in a light-purple solution and was allowed to proceed at this temperature for 72 hours. Afterwards, the reaction mixture was cooled to room temperature and dissolved using methanol (200 mL). To this solution, Fe(acac)3 (6.71 g, 19.0 mmol, 1 .0 equiv.) was added, resulting in a strong darkening of the reaction mixture. The reaction was allowed to proceed at room temperature for 16 hours. The dark suspension was filtered, and the material on the filter washed with MeOH (2 x 30 mL), resulting in a violet residue and a brown filtrate. The residue was air-dried on the filter for 2 hours, and further dried under reduced pressure at room temperature for 2 hours. The Fe(diaminotrisphenolate) complex was isolated as a violet powder (8.76 g, 74.3 %).

[0118] Elemental analysis: calcd. for C28H3oCl3FeN204: C 54.18, H 4.87, N 4.51 ; found: C 54.45, H 4.90, N 4.46.

[0119] Example 16 (compound B-7)

[0120] The preparation of a [Fe(diamonotrisphenolate)] complex in a one pot, two step procedure according to the below scheme is described. This procedure allows for the preparation of a [Fe(diamonotrisphenolate)] complex without isolation of the ligand from the reaction mixture. paraformaldehyde

[0121] Neat, 90 °C, 72 h

[0122] To a 250 mL round bottom, 2,4-dichlorophenol (10.1 1 g, 62.0 mmol, 3.26 equiv.), paraformaldehyde (1.80 g, 60.0 mmol, 3.16 equiv.), 2-((2- aminoethyl)amino)ethan-1 -ol (2.08 g, 20.0 mmol, 1.05 equiv.) and a big egg- shaped stirring bar were added. The reaction was heated to 90 °C resulting in a purple solution and was allowed to proceed at this temperature for 72 hours. Afterwards, the reaction mixture was cooled to room temperature and dissolved using methanol (200 mL). To this solution, Fe(acac)3 (6.71 g, 19.0 mmol, 1 .0 equiv.) was added, resulting in a strong darkening of the reaction mixture. The reaction was allowed to proceed at room temperature for 16 hours. The dark suspension was filtered, and the material on the filter washed with MeOH (2 x 30 mL), resulting in a dark red residue and a brown filtrate. The residue was air-dried on the filter for 2 hours, and further dried under reduced pressure at room temperature for 2 hours. The Fe(diaminotrisphenolate) complex was isolated as a dark red powder (1 .95 g, 15.0 %).

[0123] Elemental analysis: calcd. for C25H2iCl6FeN2O4: C 44.03, H 3.10, N 4.11 ; found: C 43.95, H 3.13, N 4.09.

[0124] Example 17

[0125] In this example the activity of the compounds B-4, B-5, B-6 and B-7 was tested as homogeneous catalyst in the below reaction of styrene oxide and carbon dioxide to prepare 4-phenyl-1 ,3-dioxolan-2-one. The reactions were carried out in a mixture of styrene oxide (0.42 mL) and propylene carbonate (1 .40 mL), using 0.8 mol% of compound B-4, B-5, B-6 or B-7 with respect to styrene oxide and 1 .6 mol% of a halogen salt with respect to styrene oxide.

[0126] In a Schlenk reaction flask were added 0.8 mol% of either compound B- 4, B-5, B-6 or B-7 (with respect to styrene oxide) and 1 .6 mol% of either [Bu4N](Br), [Bu4P](Br) or [BuP(Ph)3](Br) (with respect to styrene oxide). The Schlenk flask was put on vacuum and subsequently refilled with CO2 gas using a balloon at ambient pressure, after which this procedure was repeated twice. Subsequently, under CO2 gas outflow, propylene carbonate (1.40 mL) and styrene oxide (0.42 mL) were added. The Schlenk flask was placed in a 100 °C oil bath. After 2 and 6 hours the conversion was measured and listed for the different catalysts in Table 1 . The main product was 4-phenyl-1 ,3- dioxolan-2-one. Table 1

[0127] This example shows the higher catalytic activity of a homogeneous catalyst wherein R1 or R2 or R1 and R2 of the diaminotrisphenol compound are chloro groups and wherein the metal is iron. The reaction is performed in the presence of a halogen salt, namely a quaternary ammonium halogen salt or a quaternary phosphonium halogen salt.

[0128] Example 18 (Compound C-1 )

[0129] The preparation of a [Ga(diaminotrisphenolate)- propyl (trimethoxy)silane] according to the below scheme is described.

[0130] Under a nitrogen atmosphere, [Ga(diaminotrisphenolate)] of Example 2 (5.45 g, 9.50 mmol, 1.00 equiv.), (3-isocyanatopropyl)trimethoxysilane (1.95 g, 9.50 mmol, 1 .00 equiv.) and propylene carbonate (19 mL) were added to a 50 mL Schlenk flask resulting in a white suspension. The reaction was allowed to proceed at 60 °C for 16 h resulting in a light brown solution. The reaction mixture was directly used for immobilisation.

[0131] The same reaction can also be performed in pre-dried THF under a nitrogen atmosphere. After the reaction, THF was evaporated off under reduced pressure and the targeted product [Ga(diaminotrisphenolate)- propyl(trimethoxy)silane] was isolated as a slightly yellow powder in quantitative yields. NMR data of this compound was obtained in CDCh.

[0132] 1H NMR (300 MHz, CDCh) 5 7.07 - 6.25 (m, 6H, Ar-H), 5.98 (s, 1 H, NH), 4.26 (d, J = 13.5 Hz, 1 H, CH2), 3.96 (d, J = 13.5 Hz, 1 H, CH2), 3.74 (m, 2H, CH2), 3.64 (m, 1 H, CH2), 3.61 - 3.47 (m, 6H, Ar-CH2)), 3.40 (m, 1 H, CH2), 3.19 - 3.01 (m, 2H, CH2), 2.93 - 2.74 (m, 2H, CH2), 2.35 - 2.02 (m, 15H, ArCH3), 1 .92 - 1 .80 (m, 3H, Ar-CH3), 1.71 - 1 .57 (m, 1 H, CH2), 1 .43 (s, 9H, Si(OCH3)3, 1 .31 - 1 .16 (m, 1 H, CH2), 0.73 - 0.44 (m, 2H, SiCH2).

[0133] 13C-NMR (75 MHz, CDCh) 5 158.58, 157.41 (br), 155.55, 132.08, 131 .53, 128.61 , 127.69, 126.31 , 124.16, 120.88, 116.60, 77.59, 77.16, 76.74, 67.99 (THF, CH2O), 51 .95, 50.58, 43.43, 30.35, 26.95, 25.64 (THF, CH2), 23.22, 20.41 , 16.55, 16.24, 15.76, 8.54, 6.33.

[0134] FT-IR (ATR): 1728 cnr1(s, RNH-C(O)-OR’)

[0135] Example 19

[0136] Under an nitrogen atmosphere, a mixture of [Ga(diaminotrisphenolate)- propyl(trimethoxy)silane] of Example 3, 3-N,N- dimethylaminopropyltrimethoxysilane and 3- (tributyl)ammoniumpropyltrimethoxysilane bromide were added to a 50 mL Schlenk flask to a total volume of 18 mL of propylene carbonate (PC) resulting in a slightly yellow solution. The compositions of the (co-)catalyst(s) solutions are listed in Table 2 below.

[0137] Table 2

[0138] Ga:N:N+ is the molar ratio of the gallium diaminotrisphenolate complex (Ga), amine (N) and ammonium salt (N+) as applied during the immobilisation procedure

[0139] Using a Radleys MYA 4 reaction system equipped with a top stirrer, silica (10 g, SP 540-11508, Grace GmbH, 35 A, 40-60 pm) was dispersed in propylene carbonate (75 mL) and heated to 130 °C over a period of 45 minutes. Thereafter, a solution consisting of [Ga(diaminotrisphenolate)- propyl(trimethoxy)silane] as obtained in Example 13 (3.0 mL of a 0.5 M propylene carbonate solution), 3-(tributyl)ammoniumpropyltrimethoxysilane bromide (12 mL of a 0.5 M acetonitrile solution) and 3-N,N- dimethylaminopropyltrimethoxysilane (328 pL) in 3 mL of propylene carbonate was added over 3 hours using a syringe pump. The reaction mixture was allowed to stir for an additional 18 hours at 130 °C after which the reaction mixture was cooled to room temperature. The resulting slightly yellow suspension was filtered using a glass fibre filter (Whatman, 1820-055) and washed with propylene carbonate (2 x 20 mL) followed by ethyl acetate (1 x 20 mL) resulting in a slightly yellow powder residue and slightly yellow solution as filtrate. Afterwards, the residue was dried in a vacuum oven at 70 °C at 5 mbar, for 2 hours. This material was used for catalysis as the heterogeneous catalyst 19c. For compositions 19a, 19b and 19d heterogeneous catalysts 19a, 19b and 19d were prepared in a similar manner.

[0140] Example 20

[0141] In this example the catalytic activity of the heterogeneous catalyst 19a- 19d obtained in Example 4 were tested in the below reaction of styrene oxide and carbon dioxide to prepare 4-phenyl-1 ,3-dioxolan-2-one.

[0142] In a Schlenk reaction flask, 98.06 mg of the heterogeneous catalyst, was heated to 100 °C and put on vacuum. The flask was refilled with CO2 gas using a balloon at ambient pressure after which the propylene carbonate (3.30 mL) and styrene oxide (1 mL) was added. The flask was purged with CO2 and the stirring was started. After 20 hours the conversion was measured and listed for the different catalysts in Table 3. The main product was 4-phenyl-1 ,3-dioxolan-2-one.

[0143] Example 21

[0144] Example 20 was repeated except that also 1 ,4-dibromobutane (DBB) was added to the flask. After 20 hours the conversion was measured and listed for the different catalysts and amounts of DBB relative to styrene oxide (StO) in Table 3. The main product was 4-phenyl-1 ,3-dioxolan-2-one.

[0145] Table 3

[0146] The results in Table 3 show that the presence of DBB has an improved effect on conversion. Especially when in preparation no halogen salt or relatively less halogen salt is immobilised. It is believed that DBB reacts with the immobilised tertiary amine to form the immobilised halogen salt by the Menshutkin reaction. Further it shows that the presence of the immobilised halogen salt is required for a high catalytic activity. The results in Table 6, 9, 10, 13, 14, 17, 18, 21 , 22, 25, 26, 29 and 30 also support this finding.

[0147] Example 22

[0148] In this example the catalytic activity of the heterogeneous catalysts used in example 20 and 21 was tested for its recyclability in the reaction of styrene oxide and carbon dioxide to prepare 4-phenyl-1 ,3-dioxolan-2-one. After the first run (Run 1 ), the stirring was stopped, and the solid catalyst allowed to settle to the bottom of the Schlenk reaction flask. Thereafter, the solvent phase of the reaction mixture was removed. Then, ethyl acetate (4 mL) was added, the reaction mixture was stirred for 15 minutes before letting the solid catalyst to settle to the bottom of the Schlenk reaction flask. The solvent phase of the reaction mixture was removed. This washing procedure using ethyl acetate was performed twice in total. Then, the Schlenk reaction flask was heated to 100 °C and put on vacuum. The flask was refilled with CO2 gas after which the propylene carbonate (3.30 mL), styrene oxide (1 mL) and 1 ,4-dibromobutane (DBB, 20.92 pL) were added. The flask was purged with CO2 and the stirring was started. After 20 hours the conversion was measured and listed for the different catalysts in Table 4 as Run 2. The main product was 4-phenyl-1 ,3-dioxolan-2-one.

[0149] Table 4

[0150] Example 23

[0151] The so-called ‘click’ reaction’ of Example 18 was repeated starting with the Al(diaminotrisphenolate) from Example 8 with (3- isocyanatopropyl)trimethoxysilane , in propylene carbonate / THF at 60 °C. Example 24

[0152] Immobilisation of the material from Example 23, was performed in a similar fashion as described in Example 19 resulting in catalyst 24a and 24b having a composition as presented in Table 5.

[0153] Table 5

[0154] AI:N:N+ is the molar ratio of the aluminium diaminotrisphenolate complex (Al), amine (N) and ammonium salt (N+) as applied during the immobilisation procedure

[0155] Example 25

[0156] In this example the catalytic activity of the heterogeneous aluminium catalyst 24a-24b obtained in Example 24 were tested in the below reaction of styrene oxide and carbon dioxide to prepare 4-phenyl-1 ,3-dioxolan-2-one, similar to Example 20. See Table 6 below.

[0157] Example 26

[0158] Example 25 was repeated except that also 1 ,4-dibromobutane (DBB) was added to the flask. After 20 hours the conversion was measured and listed for the different catalysts and amounts of DBB relative to styrene oxide (StO) in Table 6. The main product was 4-phenyl-1 ,3-dioxolan-2-one. Table 6.

[0159] Example 27 The so-called ‘click’ reaction’ of Example 18 was repeated starting with the Fe(diaminotrisphenolate) from Example 9 with (3- isocyanatopropyl)trimethoxysilane, in propylene carbonate / THF at 25 °C.

[0160] Example 28 Immobilisation of the material from Example 27 was performed in a similar fashion as described in Example 19 resulting in catalyst 28a and 28b having a composition as presented in Table 7. The immobilised iron complex is represented by the following formula:

[0161]

[0162] Table 7

[0163] Fe:N:N+ is the molar ratio of the iron diaminotrisphenolate complex (Fe), amine (N) and ammonium salt (N+) as applied during the immobilisation procedure

[0164] ICP-MS analysis of the immobilised Fe(diaminotrisphenolate) complex as prepared in this example is provided in Table 8 below. Table 8

[0165] N / A= not applicable

[0166] Table 8 shows the molar ratio of the iron diaminotrisphenolate complex (Fe), amine (N) and ammonium salt (N+) as immobilised on the carrier surface. The results of catalyst 28b show that after immobilisation also amine is found on the carrier surface. It is believed that part of the halogen salt converts to an amine by means of the reversed Menshutkin reaction. The same is seen in the ICP-MS analysis of different catalysts as reported in tables 12, 16, 20, 24 and 28.

[0167] Example 29

[0168] Examples 20 and 21 were repeated with iron catalysts 28a and 28b.

[0169] The results are presented in Table 9.

[0170] Table 9 Example 30

[0171] Example 22 was repeated with iron catalysts 28a and 28b. The results are presented in Table 10. Table 10

[0172] Example 31

[0173] The so-called ‘click’ reaction’ of Example 18 was repeated starting with the Fe(diaminotrisphenolate) from Example 10 with (3- isocyanatopropyl)trimethoxysilane, in propylene carbonate / THF at 25 °C.

[0174] Example 32

[0175] Immobilisation of the material from Example 31 was performed in a similar fashion as described in Example 19 resulting in catalyst 32a and 32b having a composition as presented in Table 1 1 .

[0176] Table 11

[0177] Fe:N:N+ is the molar ratio of the iron diaminotrisphenolate complex (Fe), amine (N) and ammonium salt (N+) as applied during the immobilisation procedure ICP-MS analysis of the immobilised Fe(diaminotrisphenolate) complex as prepared in this example is provided in Table 12 below. Table 12

[0178] Molar ratio of the iron diaminotrisphenolate complex (Fe), amine (N) and ammonium salt (N+) as immobilised on the carrier surface. N / A = not applicable Example 33

[0179] Examples 20 and 21 were repeated with iron catalysts 32a en 32b. The results are presented in Table 13.

[0180] Table 13 Example 34

[0181] Example 22 was repeated with iron catalysts 32a and 32b. The results are presented in Table 14. Table 14

[0182] Example 35

[0183] The so-called ‘click’ reaction’ of Example 18 was repeated starting with the Fe(diaminotrisphenolate) from Example 14 with (3- isocyanatopropyl)trimethoxysilane, in propylene carbonate / THF at 25 °C.

[0184] Example 36

[0185] Immobilisation of the material from Example 35 was performed in a similar fashion as described in Example 19 resulting in catalyst 36a and 36b having a composition as presented in Table 15.

[0186] Table 15

[0187] Fe:N:N+ is the molar ratio of the iron diaminotrisphenolate complex (Fe), amine (N) and ammonium salt (N+) as applied during the immobilisation procedure ICP-MS analysis of the immobilised Fe(diaminotrisphenolate) complex as prepared in this example is provided in Table 16 below. Table 16

[0188] Molar ratio of the iron diaminotrisphenolate complex (Fe), amine (N) and ammonium salt (N+) as immobilised on the carrier surface. N / A = not applicable Example 37

[0189] Examples 20 and 21 were repeated with iron catalysts 36a and 36b.

[0190] The results are presented in Table 17.

[0191] Table 17 Example 38

[0192] Example 22 was repeated with iron catalysts 36a and 36b. The results are presented in Table 18.

[0193] Table 18

[0194] Example 39

[0195] The so-called ‘click’ reaction’ of Example 18 was repeated starting with the Fe(diaminotrisphenolate) from Example 12 with (3- isocyanatopropyl)trimethoxysilane, in propylene carbonate / THF at 25 °C.

[0196] Example 40

[0197] Immobilisation of the material from Example 39 was performed in a similar fashion as described in Example 19 resulting in catalyst 40a and 40b having a composition as presented in Table 19.

[0198] Table 19

[0199] Fe:N:N+ is the molar ratio of the iron diaminotrisphenolate complex (Fe), amine (N) and ammonium salt (N+) as applied during the immobilisation procedure ICP-MS analysis of the immobilised Fe(diaminotrisphenolate) complex as prepared in this example is provided in Table 20 below.

[0200] Table 20

[0201] Molar ratio of the iron diaminotrisphenolate complex (Fe), amine (N) and ammonium salt (N+) as immobilised on the carrier surface. N / A = not applicable

[0202] Example 41

[0203] Examples 20 and 21 were repeated with iron catalysts 40a and 40b.

[0204] The results are presented in Table 21 .

[0205] Table 21

[0206] Example 42

[0207] Example 22 was repeated with iron catalysts 40a and 40b. The results are presented in Table 22. Table 22

[0208] Example 43

[0209] The so-called ‘click’ reaction’ of Example 18 was repeated starting with the Fe(diaminotrisphenolate) from Example 13 with (3- isocyanatopropyl)trimethoxysilane, in propylene carbonate / THF at 25 °C.

[0210] Example 44

[0211] Immobilisation of the material from Example 43 was performed in a similar fashion as described in Example 19 resulting in catalyst 44a and 44b having a composition as presented in Table 23.

[0212] Table 23

[0213] Fe:N:N+ is the molar ratio of the iron diaminotrisphenolate complex (Fe), amine (N) and ammonium salt (N+) as applied during the immobilisation procedure

[0214] ICP-MS analysis of the immobilised Fe(diaminotrisphenolate) complex as prepared in this example is provided in Table 24 below. Table 24

[0215] Molar ratio of the iron diaminotrisphenolate complex (Fe), amine (N) and ammonium salt (N+) as immobilised on the carrier surface. N / A = not applicable

[0216] Example 45

[0217] Examples 20 and 21 were repeated with iron catalysts 44a and 44b.

[0218] The results are presented in Table 25. Table 25

[0219] Example 46

[0220] Example 22 was repeated with iron catalysts 44a and 44b. The results are presented in Table 26. Table 26

[0221] Example 47

[0222] The so-called ‘click’ reaction’ of Example 18 was repeated starting with the Fe(diaminotrisphenolate) from Example 10 with (3- isocyanatopropyl)trimethoxysilane, in propylene carbonate / THF at 25 °C.

[0223] Under a nitrogen atmosphere, Fe(diaminotrisphenolate) of Example 10 (1 .12 g, 2.00 mmol, 1 .00 equiv.), 5 mL pre-dried THF, 10 mL propylene carbonate and (3-isocyanatopropyl)trimethoxysilane (0.38 mL, 2.00 mmol, 1 .00 equiv.) were added to a 50 mL Schlenk flask resulting in a purple solution. The reaction was allowed to proceed at 25 °C for 16 h resulting in a purple-brown solution. The reaction mixture was directly used for immobilisation.

[0224] Example 48

[0225] (Co-)immobilisation of the material from Example 47 with 3- (tripropyl)phosphoniumpropyltrimethoxysilane bromide and 3-N,N- dimethylaminopropyltrimethoxysilane was performed in a similar fashion as (co-)immobilisation employing 3-(tributyl)ammoniumpropyltrimethoxysilane bromide and 3-N,N-dimethylaminopropyltrimethoxysilane as described in Example 19, but at a scale of 5.0 g silica instead of 10 g silica as in Example 19. The compositions of the (co-)catalyst(s) solutions are listed in Table 27 below. Table 27

[0226] Fe:N:P+ is the molar ratio of the iron diaminotrisphenolate complex (Fe), amine (N) and phosphonium salt (P+) as applied during the immobilisation procedure

[0227] 3-(tripropyl)phosphoniumpropyltrimethoxysilane bromide was prepared by stirring (3-bromopropyl)trimethoxysilane (4.86 g, 20.0 mmol, 1.00 equiv.) and tri-n-butylphosphine (3.20 g, 20.0 mmol, 1 .00 equiv.) under a nitrogen atmosphere in a 50 mL Schlenk flask at 25 °C for 7 days. The resulting clear, thick liquid was washed with 15 mL pre-dried diethyl ether in the Schlenk flask, and subsequently dried under vacuum at 25 °C for 30 minutes. The product was characterised by1H NMR and31P NMR:1H NMR (400 MHz, DMSO-d6); 5 3.50 (s, 9H), 2.28 - 2.12 (m, 8H), 1.61 - 1 .45 (m, 6H), 1 .03 (t, J = 7.3 Hz, 9H), 0.77 (t, J = 8.0 Hz, 2H).31P NMR (162 MHz, DMSO-6): 5 31 .76. The NMR data indicates that the desired product was formed. The product was stored under a nitrogen atmosphere at 25 °C until use. Immediately before use, the compound was dissolved in propylene carbonate resulting in a 0.50 M solution.

[0228] Under a nitrogen atmosphere, an immobilisation mixture of [Fe(diaminotrisphenolate)-propyl(trimethoxy)silane] of Example 47 (5.77 mL of a 0.133 M THF / propylene carbonate solution, 0.75 mmol), 3-N,N- dimethylaminopropyltrimethoxysilane (0.41 mL, 1 .88 mmol) and 3- (tripropyl)phosphoniumpropyltrimethoxysilane bromide (3.76 mL of a 0.50 M propylene carbonate solution, 1 .88 mmol) were added to a 50 mL Schlenk flask together with propylene carbonate (5.06 mL) to a total volume of 15 mL, resulting in a dark solution.

[0229] Using a Radleys MYA 4 reaction system equipped with a top stirrer, silica (5.0 g, SP 540-11508, Grace GmbH, 35 A, 40-60 pm) was dispersed in propylene carbonate (35 mL) and heated to 130 °C over a period of 45 minutes. Thereafter, the just prepared 15 mL immobilisation mixture was added over 3 hours using a syringe pump. The reaction mixture was allowed to stir for an additional 18 hours at 130 °C after which the reaction mixture was cooled to room temperature. The resulting slightly yellow suspension was filtered using a glass fibre filter (Whatman, 1820-055) and washed with propylene carbonate (2 x 30 mL) followed by ethyl acetate (1 x 30 mL) resulting in a slightly brown powder residue and brownish solution as filtrate. Afterwards, the residue was dried in a vacuum oven at 70 °C at 5 mbar, for 16 hours. This material was used for catalysis as the heterogeneous catalyst 48a. For composition 48b heterogeneous catalyst 48b was prepared in a similar manner.

[0230] ICP-MS analysis of the immobilised Fe(diaminotrisphenolate) complex as prepared in this example is provided in Table 28 below.

[0231] Table 28

[0232] Molar ratio of the iron diaminotrisphenolate complex (Fe), amine (N) and phosphonium salt (P+) as immobilised on the carrier surface.

[0233] The results for catalyst 48b show that immobilised tertiary amine is detected while no amine is immobilised. It is believed that this could be the result of some decomposition of the metal complex resulting in the formation of immobilised amine. Example 49

[0234] Examples 20 and 21 were repeated with iron catalysts 48a and 48b.

[0235] The results are presented in Table 29. Table 29

[0236] Example 50

[0237] Example 22 was repeated with iron catalysts 44a and 44b. The results are presented in Table 30.

[0238] Table 30

[0239] Example 51

[0240] Complexation with gallium of a diaminotrisphenol ligand where n = 3 has been attempted employing diaminotrisphenol compound A-5 from Example 6. The reaction was performed in a similar manner as the successful complexation with gallium as described in Example 7 of diaminotrisphenol compound A-1 of Example 1 , where n = 2, employing gallium ethoxide. For both compounds R1 , R2, m and R3 are the same, the only difference between these compounds being the value of n.

[0241] Under an atmosphere of dinitrogen, a mixture of diaminotrisphenol compound A-5 of Example 6 (521 mg, 1 .00 mmol, 1 .00 equiv.), gallium ethoxide (205 mg, 1 .00 mmol, 1 .00 equiv.) and pre-dried THF (10 mL) was stirred at 25 °C for 16 h. The light yellow, turbid reaction mixture was then filtered over Celite filter aid and washed with THF (2 x 5 mL) resulting in a clear slightly yellow solution as the filtrate. Afterwards, the THF was evaporated off under reduced pressure and the resulting yellow powder further dried under reduced pressure at room temperature for 30 minutes.1H NMR analysis in CDCh of this material reveals it to be compound A-5, the starting material, indicating unsuccessful complexation.

[0242] This indicates a preference for metal complexation of diaminotrisphenol compounds with n = 2 (such as compound A-1 , Example 1) over diaminotrisphenol compounds with n = 3 (such as compound A-5, Example 6).

Claims

CLAIMS1 . A diaminotrisphenol compound according to the following formula: following formula:wherein R1 and R2are hydrogen or a substituent , R2is a hydroxyl group, carboxylic acid group, an ester group or a group comprising alkyl(trialkoxy)silane or alkyltrichlorosilane and wherein n is 2 or 3 and m is 2 or higher.

2. A diaminotrisphenol compound according to claim 1 , wherein n is 2.

3. A diaminotrisphenol compound according to any one of claims 1 -2, wherein R2is a hydroxyl group.

4. A diaminotrisphenol compound according to any one of claims 1 -2, wherein R2comprises a alkyl(trialkoxy)silane or alkyltrichlorosilane group and wherein the alkyl group preferably has 2 to 6 carbon atoms and the alkoxy group has preferably 1 to 3 carbon atoms.

5. A diaminotrisphenol compound according to any one of claims 1 -4, wherein R1and R2is hydrocarbon substituent or a functional group substituent or a combination of a hydrocarbon substituent and afunctional group substituent.

6. A diaminotrisphenol compound according to claim 5, wherein R1 and / orR2 are chloro.

7. A diaminotrisphenol compound according to claim 5, wherein R1 andR2are methyl groups.

8. A process to prepare a diaminotrisphenol compound, by reacting a functionalised diamine with a corresponding substituted phenol which is ortho substituted with a group R1and para substituted with a group R2and formaldehyde to the diaminotrisphenol compound and water as a byproduct according to the below reaction:wherein R1 and R2are substituents other than hydrogen, R2is a hydroxyl group, carboxylic acid group, an ester group and wherein n is 2 or 3 and m is 2 or higher.

9. A process to prepare a diaminotrisphenol compound having ananchoring group starting by reacting a diaminotrisphenol compound according to any one of claims 1 -3 or 5-7 or obtainable by the process of claim 8, wherein RS is a hydroxyl group, carboxylic acid group or an ester group with a bi functional compound having a functional group which can react with the hydroxyl group, the carboxylic acid group or the ester group and provided with a functional group which can covalently bond with the surface of a solid support.

10. A process according to claim 9, wherein the functional group which can covalently bond with the surface of a solid support is an alkyl(trialkoxy)silane or alkyltrichlorosilane group.

11. A metal complex comprising the diaminotrisphenol compound of any one of claims 1 -7 and a metal.

12. A metal complex according to claim 11 , wherein the metal is any one of aluminium, gallium, indium, iron, cobalt, nickel, zinc, titanium, yttrium, samarium, neodymium and lanthanum13. A metal complex according to claim 12, wherein the metal is gallium, iron, or aluminium, preferably iron.

14. A process to prepare a metal complex according to claim 13, wherein first a diaminotrisphenol compound is prepared by a process according to any one of claims 9-10 to obtain a reaction mixture containing the diaminotrisphenol compound and wherein without isolation of the diaminotrisphenol compound from the reaction mixture a suitable gallium, aluminium or iron compound is added to the reaction mixture to obtain the corresponding metal complex.

15. Supported catalyst comprising an immobilised metal complex of anyone of claims 11 -14.

16. Supported catalyst according to claim 15, comprising carrier particles having a carrier surface, to which carrier surface the metal-complex is immobilised and a halogen salt is immobilised such that the metalcomplex and the halogen salt are each individually immobilised to the carrier surface.

17. Supported catalyst according to claim 16, wherein the halogen salt is an ammonium or phosphonium halogen salt.

18. Supported catalyst according to any one of claims 16-17, wherein the molar ratio of the separately immobilised halogen salt and the metal complex is higher than 2:1 and below 10:1 .

19. Supported catalyst according to any one of claims 16-18, wherein also an amine is individually immobilised to the carrier surface.

20. Supported catalyst according to claim 19, wherein the ratio between the separately immobilised amine and the metal complex is below 10:1 .21 . A process to prepare a cyclic carbonate by reacting an epoxide compound and carbon dioxide in the presence of a metal complex according to any one of claims 11 -14 and a quaternary ammonium halogen salt or a quaternary phosphonium halogen salt.

22. The process according to claim 21 , wherein the metal is iron and the diaminotrisphenol compound is according to claim 6.

23. A process to prepare a cyclic carbonate by reacting an epoxide compound and carbon dioxide in the presence of the supported catalystof any one of claims 15-20 and a non-immobilised halogen compound.

24. The process according to claim 23, wherein the supported catalyst is present as a suspension in the cyclic carbonate.

25. The process according to claim 23, wherein the heterogeneous catalyst is present as part of a fixed bed in a fixed bed reactor.

26. The process according to any one of claims 23-25, wherein the halogen compound is an aryl halogen compound or an alkyl halogen compound.

27. The process according to claim 26, wherein the halogen compound is a C3-C10 alkyl bromide.

28. The process according to claim 27, wherein the alkyl bromide is any one of propyl bromide, butyl bromide, pentyl bromide, hexyl bromide, heptyl bromide, octyl bromide, 1 ,2-dibromoethane, 1 ,3-dibromopropane, 1 ,4-dibromobutane, 1 ,5 dibromopentane and 1 ,6-dibromohexane.

29. The process according to any one of claims 23-28, wherein the epoxide compound has 2 to 8 carbon atoms.

30. The process according to claim 29, wherein the epoxide compound is ethylene oxide, propylene oxide, butylene oxide, pentene oxide, glycidol, styrene oxide or fluoroethylene oxide.

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