Effect of phenoxy ligands on catalytic properties of titanium half-sandwich complexes/MAO systems

A study on the effect of phenoxy ligands of an donor or acceptor character in titanium half-sandwich catalytic systems of a general formula LTiCl2(OC6H4X-p)/MAO (where L is cyclopentadienyl, indenyl or pentamethylcyclopentadienyl; X = NO2, Cl, H, CH3, t-C4H9, OCH3; MAO: methylalumoxane) on their activity and selectivity in the reactions of polymerization of olefins and styrene and of their co-polymerization, showed that the effect of coordination of the polymerization centers by the phenyl rings substituted with donor groups is involved here. The effect resulted in the formation of polymers of a lower molecular weight and was crucial to the composition of the products obtained: polymer or oligomer, co-polymer or homopolymer mixture.

Graphical abstractAuxiliary phenoxy ligands of donor character in the titanium half-sandwich complex/MAO systems, can act as additional donor ligands in titanium active catalytic centers resulting in increasing the rate of termination step in olefin and styrene polymerization.Auxiliary phenoxy ligands of acceptor character in the titanium half-sandwich complex/MAO systems, enhances the rate of propagation steps in olefin and styrene polymerization processes resulting in high molecular weight ethylene and propylene polymers and enable ethylene–high olefin and ethylene–styrene copolymers formation. Ethylene polymerization in the presence of the CpTiCl2(OC6H4X-p)/MAO catalytic system, where X = NO2, Cl, H, CH3, t-C4H9, OCH3 under atmospheric pressure. Figure optionsDownload full-size imageDownload as PowerPoint slide