ATOM-TRANSFER POLYMERIZATION OF METHYL-METHACRYLATE - USE OF CHIRAL ARYL ALKYL PYRIDYLMETHANIMINE LIGANDS - WITH COPPER(I) BROMIDE AND AS STRUCTURALLY CHARACTERIZED CHIRAL COPPER(I) COMPLEXES/

The use of chiral catalysts in the living radical polymerisation of me thyl methacrylate via atom transfer polymerisation (ATP) has been inve stigated in an effort to control the stereochemistry of the polymer ba ckbone. Two enantiomerically pure chiral catalysts have been prepared and used in the ATP of methyl methacrylate: the structurally character ised complex, bis[N-(1-phenylethyl)-2-pyridylmethanimine] copper(I) te trafluoroborate, [Cu(C14H14N2)(2)][BF4], and the reaction product of c opper(I) bromide with N-(1-cyclohexylethyl)-2-pyridylmethanimine, [Cu( C14H20N2)(2)][Br]. Both catalysts were found to be suitable for the AT P of methyl methacrylate in conjunction with either ethyl 2-bromo-2-me thylpropanoate in xylene at 90 degrees C or 4-methoxybenzenesulfonyl c hloride in diphenyl ether at 90 degrees C. The system yields polymer o f relatively narrow polydispersity; however, the use of these chiral c atalysts did not significantly affect the stereochemistry of the polym er backbone. This may be due to the chiral centre being too distant fr om the propagating site to exert any influence over the monomer additi on step, or that the reaction proceeds via a completely free-radical m echanism. This is, however, the first time a discrete, structurally ch aracterised copper complex has been used as an effective ATP catalyst. The bond lengths of the complexed ligand indicate the oxidation state of the copper to be + 1 in the complex.