Radically Initiated Group Transfer Polymerization of Methacrylates by Titanium Amino-Phenolate Complexes

Radical initiation
of methyl methacrylate polymerizations mediated
by titanium amino-phenolate complexes gave exceptional control without
the need for any cocatalyst or activator. The polymerization proceeds
not by a classical controlled radical or coordination insertion mechanism
but via a unique bimetallic group transfer process. Detailed experimental
and computational studies support a polymerization mechanism with
a titanium­(IV)-enolate complex and a second titanium­(III) complex
that delivers an activated monomer and provides new insight into both
titanium-mediated radical reactions and polymerizations.