MECHANISM OF SYNDIOTACTIC-SPECIFIC POLYMERIZATION OF STYRENE

Perusal of literature data and some new results concerning syndiotacti c-specific polymerization of styrene suggest a reaction mechanism acco unting for the steric control. Key features of the proposed mechanism are stereorigid eta(n) coordination of the growing chain end and diast ereoselective coordination of the monomer imposed by direct interactio ns with the ancillary ligand of the metal complex, a pseudotetrahedral chiral Ti(III) or Zr(III) cation, which inverts its configuration aft er every syndiospecific insertion step.