Living polymerization of 1,3-butadiene catalyzed by half-titanocene complex bearing dibenzhydryl-substituted aryloxide ligand

Abstract

Half-titanocene complexes bearing dibenzhydryl-substituted aryloxide ligands (2a−2d) were prepared. Among them, 2c adopted a three-legged distorted tetrahedral geometry evidenced by X-ray crystallography. The poly-1,3-butadiene with high molecular weight and narrow molecular weight distribution was obtained by using these complexes as the catalysts activated with methylaluminoxane (MAO). The catalytic activities of the complexes depended on their structures. The Ti-O-C bond in the complexes with large angle afforded them with higher activity, while Cp*-based complexes exhibited lower activities than the Cp-based analogues. The activity of complex increased with increasing the polymerization temperature while the selectivity remained no change, indicating the high thermal stability. Furthermore, the polymerization of 1,3-butadiene catalyzed by 2a/MAO at 0 °C has been found in a living fashion.