Comparative study of the coordination chemistry and lactide polymerization of alkoxide and amide complexes of zinc and magnesium with a beta-diiminato ligand bearing ether substituents.
A series of beta-diiminato complexes of the form (BDI-3)MX where (BDI-3) = [CH(CMeNC(6)H(4)-2-OMe)(2)]; M = Zn, Mg; X = O(i)()Pr, O(t)()Bu, or N(SiMe(3))(2) has been synthesized. The (BDI-3) ligand is bidentate in (BDI-3)ZnN(SiMe(3))(2) and tetradentate in (BDI-3)MgN(SiMe(3))(2). The alkoxide complexes are shown to be active for lactide polymerization. Polymerization of rac-lactide with (BDI-3)ZnO(i)Pr gives a moderate preference for heterotactic PLA. Polymerization of rac-lactide with [(BDI-3)MgO(t)Bu](2) shows a slight preference for heterotactic PLA in CH(2)Cl(2) but is highly stereoselective in THF in the production of heterotactic PLA.
Chisholm
Malcolm H
MH
Department of Chemistry, The Ohio State University, Columbus, 43210-1185, USA. chisholm@chemistry.ohio-state.edu
Gallucci
Judith C
JC
Phomphrai
Khamphee
K