SN2-Like Mechanism for the Ziegler−Natta Syndiospecific Catalysis atab InitioLevel

The syndiospecific polymerization of propene has been known since the 1960s by means of homogeneous vanadium-based catalysts. 1 In the 80s, the molecular mechanism of fluxional chiral complexes has been proposed. 2 The metallocenic revolution in isoand syndiospecific polymerization 3 and, in the new century, the discovery of the octahedral postmetallocenic catalysts 4 have had important consequences to understand the catalytic cycle, and the fluxional mechanism has been revaluated. 5 The complexes give chain-end controlled 6 polymerization by means of secondary insertion of propene.