Polymerization catalyst obtained by reaction of a rare earth borohydride, a boron activator i.e. an ammonium borate or a carbenium borate and an aluminum compound

摘要

Polymerization catalyst obtained by reaction of: a rare earth borohydride; a boron activator i.e. an ammonium borate comprising an ammonium cation that is a protonated amine or an ammonium ion and a non-coordinating borate anion, a carbenium borate containing a carbenium cation and a non-coordinating borate anion, or a borane carrying the groups having inductive attractor effect; and an aluminum compound containing an aluminum-carbon bond or aluminum-hydrogen bond. Independent claims are included for: (1) preparing a polymer, comprising contacting ethylenically unsaturated monomers with the catalyst under polymerization conditions; and (2) composition of polyisoprene with 1,4-cis stereochemistry susceptible to be obtained by the process, optionally carrying organometallic terminal groups.