Polymerization of 1,3‐butadiene, 4‐methyl‐1,3‐pentadiene and styrene with catalyst systems based on biscyclopentadienyl derivatives of titanium

Abstract 1,3‐Butadiene, 4‐methyl‐1,3‐pentadiene and styrene were polymerized with dicyclopentadienyltitanium dichloride/methylaluminoxane (Cp2TiCl2/MAO) and dicyclopentadienyltitanium chloride/MAO (Cp2TiCl/MAO). These systems are less active than cyclopentadienyltitanium trichloride/MAO (CpTiCl3/MAO), but show the same stereospecificity as the latter; they give predominantly cis‐1,4‐polybutadiene, 1,2‐syndiotactic poly(4‐methyl‐1,3‐pentadiene) and syndiotactic polystyrene. Cp2TiCl/MAO is much more active than Cp2TiCl2/MAO; this is probably due to the fact that in the reaction of Cp2TiCl2 with MAO, only a small amount of Ti(IV) is reduced to Ti(III), which is the active species in the polymerization of styrene and 1,3‐dienes. An interpretation of the structure of the active species in Cp2TiCl/MAO is reported.