Patent ID: 8193112

Claim:
A catalyst for cyclic lactone polymerization of the formula I: [L-M-R 1 ] + X − (I) wherein L is a neutral ancillary ligand of the formula (V) Y is O or S; R 3 is selected from C 1-20 alkyl, C 3-20 cycloalkyl, C 6-14 aryl and Si(R c ) 3 , said latter 4 groups being optionally substituted with one or more substituents independently selected from C 1-6 alkyl, fluoro-substituted C 1-6 alkyl, phenyl, phenyl substituted with one to five C 1-6 alkyl, and halo, and R c is selected from C 1-20 alkyl, fluoro-substituted C 1-20 alkyl, C 3-20 cycloalkyl and C 6-14 aryl; R 4 and R 5 are simultaneously or independently selected from C 1-20 alkyl, C 3-20 cycloalkyl and C 6-14 aryl, said latter 3 groups being optionally substituted with one or more substituents independently selected from C 1-6 alkyl, fluoro-substituted C 1-6 alkyl and halo; R 6 and R 7 are simultaneously or independently selected from C 1-6 alkyl, fluoro-substituted C 1-6 alkyl and halo; W is H, a chiral group or —P(R 8 R 9 )═N—R 10 , R 8 , R 9 and R 10 are as defined for R 4 , R 5 and R 3 , respectively; m is 0, 1 or 2; and when m is 0, the ligand of formula (V) comprises a dibenzofuran or dibenzothiophene fused ring system; n and n′ are simultaneously or independently 0, 1, 2 or 3, M is a divalent metal suitable for cyclic lactone polymerization; R 1 is selected from halo, R a , OR a , C(O)R a , C(O)OR a , OC(O)R a , C(O)NR a R b and NR a R b , R a and R b are simultaneously or independently selected from H, C 1-10 alkyl, fluoro-substituted C 1-10 alkyl and C 6-14 aryl, wherein C 6-14 aryl is unsubstituted or substituted with one or more substituents independently selected from halo, C 1-6 alkyl, NR d R e , OR d and phenyl; R d and R e are sumultaneously or independently selected from H, C 1-10 alkyl, fluoro-substituted C 1-10 alkyl and C 6-14 aryl; and X − is a suitable non- or weakly-coordinating anion.