Molecular and supported Ti(iii)-alkyls: efficient ethylene polymerization driven by the π-character of metal–carbon bonds and back donation from a singly occupied molecular orbital

Ti(iii) alkyl species polymerize ethylene via an original mechanism, which involves back donation to the π*(C2H4) and a delocalization of the unpaired electron in the transition state of C2H4 insertion into the partially alkylidenic Ti(iii)–C bond.