Half-titanocenes for precise olefin polymerisation: effects of ligand substituents and some mechanistic aspects

Selected examples concerning effects of both cyclopentadienyl fragment (Cp') and anionic donor ligand (Y) in nonbridged modified half-titanocenes of the type, Cp'TiX2(Y) (X = halogen, alkyl), as new type of olefin polymerisation catalysts have been reviewed. These complexes displayed unique characteristics not only for ethylene (co) polymerisation but also for syndiospecific styrene polymerisation, ethylene/styrene copolymerisation; precise fine tuning of the ligand substituents plays an important role for the successful (co) polymerisation; a different mechanistic consideration for the syndiospecific styrene polymerisation, which can explain the copolymerisation behaviour in this catalysis, has also been introduced.