Elucidation of Substituent Effects in the Polymerization of Propylene Promoted by Titanium Amidinates

作者：Aharonovich Sinai; Botoshansky Mark; Balazs Yael S; Eisen Moris S^*

来源：Organometallics, 2012, 31(8): 3435-3438.

DOI：10.1021/om300068w

In polymerization reactions, the molecular weight of the polymer depends on the rates of monomer insertion, chain termination, and chain transfer. Here we do present studies indicating why chelating octahedral benzamidinate group IV complexes, which promote the polymerization of propylene with MAO, exhibit a linear free energy relationship with the steric Taft parameter. We correlate that this relationship is encountered with the para substituent of the aromatic ring, far away from the active catalytic site. A number of known events are put together to shed light on the effect of the ancillary ligands in the catalytic polymerization, and a new plausible mechanism for the process is presented.

• 出版日期2012-4-23