Synthesis of chlorotitanium(IV) Schiff-Base complexes and their application to styrene polymerization

A [TiCl2(salen)] complex and its derivatives with the formula [TiCl2(L)] [L = salen(tBu), salen(di-Me), salen(di-tBu), salen(Me)] were synthesized in high yield by reacting the Schiff-base ligands with TiCl4. [TiCl2{salen(tBu)}] and [TiCl2{salen(di-tBu)}] have been characterized by single-crystal X-ray diffraction. Styrene polymerizations carried out with [TiCl2(salen)] and its derivatives co-catalyzed by MAO yielded syndiotactic polystyrenes. The catalytic activity and syndiospecificity were dependent on the bulkiness of the; ortho substituents in the aryl ring of ligand.