A series of 1,2-ethylidene bridged bis-(benzimidazolyl, benzothiazolyl, and benzoxazolyl)
complexes with the transition metals titanium, zirconium and vanadium were synthesized and
characterized. The activation with methylalumoxane (MAO) gave ethylene polymerization
catalysts with good activities. Structure-property-relationship studies were performed in order to
investigate the influence of the hetero atoms of the ligand and to optimize the catalyst design
with suitable substituents at the ligand. The best activity (385.8 kg PE/molcat.h) was achieved
with the titanium bis-(oxazolyl) complex 23/MAO containing a methyl substituent meta to
nitrogen in the six-membered ring.