Chemoselectivity in 4‐methyl‐1,3‐pentadiene polymerization in the presence of homogeneous Ti‐based catalysts

Abstract
The homogeneous catalyst CpTiCl3‐MAO is able to produce a random copolymer of 4‐methyl‐1,3‐pentadiene with ethylene. 13C NMR analysis of the copolymers shows that after insertion of ethylene units, the next 4‐ymethyl‐1,3‐pentadiene unit can be inserted in either 1,2 or 1,4 arrangement. The high chemoselectivity observed in the 1,2‐syndiotactic homopolymerization of 4‐methyl‐1,3‐pentadiene with respect to the lower one observed in the copolymerization with ethylene is attributed to a back‐biting coordination to the Ti of the active species of the penultimate monomer unit of the growing chain.