Ring-opening polymerization by lithium catalysts: an overview.

This critical review summarizes recent developments in the preparation and application of lithium catalysts/initiators such as, alkyl lithium, alkoxy lithium and bimetallic lithium compounds for ring-opening polymerization (ROP). The ROP of cyclic esters, cyclic carbonates, cyclo-silazanes, cyclo-silanes, cyclo-siloxanes, cyclo-carboxylate, cyclic phosphirene and quinodimethanes are covered in this review. The present paper emphasizes the polymerization kinetics and the control exhibited by the different types of lithium initiators/catalysts.

Synthesis and structural studies of heterobimetallic alkoxide complexes supported by bis(phenolate) ligands: efficient catalysts for ring-opening polymerization of L-lactide.

A series of heterobimetallic titanium(IV) complexes [LTi(O(i)Pr)(mu-O(i)Pr)(2)Li(THF)(2)], [LTi(O(i)Pr)(mu-O(i)Pr)(2)Na(THF)(2)], [LTi(mu-O(i)Pr)(2)Zn(O(i)Pr)(2)], and [LTi(mu-O(i)Pr)(2)Mg(O(i)Pr)(2)] (where L = bidentate bisphenol ligands) have been synthesized and characterized including a structural determination of [L(1)Ti(mu(2)-O(i)Pr)(2)(O(i)Pr)Li(THF)(2)] (1a). These complexes were investigated for their utility in the ring-opening polymerization (ROP) of l-lactide (LA). Polymerization activities have been shown to correlate with the electronic properties of the substituent within the bisphenol ligand.