Patent ID: 8436133

Claim:
A process for preparing homo-or co-polymers of polar cyclic monomers by ring-opening polymerisation with a metallic complex of formula I: wherein R 1 , R 3 , R 4 , R 5 , R 6 and R 7 are each independently selected from hydrogen, an unsubstituted or a substituted hydrocarbyl, or an inert functional group, wherein two or more of R 1 , R 3 , R 4 , R 5 , R 6 and R 7 can be linked together to form one or more rings; wherein Z′ is one or two heteroatom(s) and n is 0 or 1; wherein Z is an atom selected from Group 14 of the Periodic Table; wherein R 2 is an alkyl or a substituted or an unsubstituted aryl group having at most 8 carbon atoms with the restriction that Z(R 2 ) 3 is a bulky group that is at least as bulky as tert-butyl, and wherein Z(R 2 ) 3 can be a substituted aryl group; wherein M is a metal of Group 3 of the periodic Table or a member of the lanthanide series; and wherein R $ is an alkyl, CH 2 SiMe 3 , CH(SiMe 3 ) 2 , OR*, or NR ** 2 , wherein R * is alkyl, aryl or lactate O-CH(CH 3 )(COOR′), and wherein R ** is SiMe 3 or SiHMe 2 .