Bimetallic catalytic complexes for the polymerisation of carbon dioxide and an epoxide

1. A process comprising copolymerizing carbon dioxide with an epoxide in the presence of a catalyst of formula (I) to prepare a polycarbonate, wherein the catalyst of formula (I) has the structure:

wherein R 1 and R 2 are independently hydrogen, alkyl, haloalkyl, aryl, halide, amine, a nitro group, an ether group, a silyl ether group, a nitrile group or an acetylide group;

R 3 is alkylene, arylene or cycloalkylene;

R 4 is H, alkyl, aryl alkylaryl;

E 1 is C, E 2 is O, S or NH or E 1 is N and E 2 is O;

X is OCOCH 3 , OCOCF 3 , OSO 2 C 7 H 7 , OSO(CH 3 ) 2 , alkyl, alkoxy, halide or amido; and

M is Zn(II), O(II), Co(H), Mg(II), Fe(II), Cr(III)-X, Co(III)-X, or Fe(III)-X.

2. The process according to claim 1 , wherein the epoxide is selected from cyclohexene oxide, propylene oxide, a substituted cyclohexene oxide, an alkylene oxide or a substituted oxirane.

3. The process as claimed in claim 1 , wherein said process is carried out at 1 atmosphere.

4. The process according to claim 1 , wherein R 1 and R 2 are independently selected from hydrogen, tBu, Me, CF 3 , phenyl, F, Cl, Br, I, NMe 2 , NEt 2 , NO 2 , OMe, OSiMe 3 , OSiEt 3 , CNMe, CN and CCPh.

5. The process according to claim 1 , wherein R 3 is a substituted or unsubstituted C 3 alkylene group.

6. The process according to claim 1 , wherein R 3 is ethylene, 2,2-dimethylpropylene, propylene, butylene, phenylene, cyclohexylene or biphenylene.

7. The process according to claim 1 , wherein R 4 is H, Me, Et, Bn, iPr, tBu or Ph.

8. The process according to claim 1 , wherein X for the catalyst of formula (I) is OCOCH 3 , OCOCF 3 , OSO 2 C 7 H 7 , OSO(CH 3 ) 2 , Et, Me, PhOEt, OMe, OiPr, OtBu, Cl, Br, I, F, N(iPr) 2 or N(SiMe 3 ) 2 .

9. The process according to claim 1 , wherein said catalyst of formula (I) has a structure selected from: