Catalysts and methods for polymer synthesis
First Claim
1. A method for the synthesis of aliphatic polycarbonates comprising the step of contacting an epoxide and carbon dioxide with a metal complex comprising a metal atom coordinated with a salen ligand, the salen ligand comprising two halves, each half coordinated to the metal atom via an imine and an oxygen atom, wherein the metal complex is characterized in that one of the two halves of the salen ligand has two or more cationic activating functional groups tethered to it and the other half has no tethered cationic activating functional groups, wherein the metal complex is of formula IVa:
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Abstract
The present invention provides unimolecular metal complexes having increased activity in the copolymerization of carbon dioxide and epoxides. Also provided are methods of using such metal complexes in the synthesis of polymers. According to one aspect, the present invention provides metal complexes comprising an activating species with co-catalytic activity tethered to a multidentate ligand that is coordinated to the active metal center of the complex.
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Citations
29 Claims
- 1. A method for the synthesis of aliphatic polycarbonates comprising the step of contacting an epoxide and carbon dioxide with a metal complex comprising a metal atom coordinated with a salen ligand, the salen ligand comprising two halves, each half coordinated to the metal atom via an imine and an oxygen atom, wherein the metal complex is characterized in that one of the two halves of the salen ligand has two or more cationic activating functional groups tethered to it and the other half has no tethered cationic activating functional groups, wherein the metal complex is of formula IVa:
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29. A metal complex of formula IVa:
Specification