The insertion of olefins into the metal�carbon bond is the fundamental step in homogenous Ziegler�Natta olefin polymerization catalyzed by group IV metal complex ion pairs. Understanding how the nature of both counterion and solvent modulates the activation parameters of the insertion reaction is important, but fundamental kinetic investigations are complicated by several reasons including high reactions rates, poor stability of ion pairs and determination of active sites.Here we report on kinetic NMR studies of the single insertion of 2-methyl-1-heptene in the Zr-C bond of model zirconaaziridinium ion pairs, [Cp2Zr(?2-CH2-NMePh)][X] [X-� = MeB(C6F5)3� or B(C6F5)4�], in solvents with different polarity. We show that using a suitable a-olefin in combination with metal ion pairs having long-term stability allowed the unprecedented evaluation of how ?H� and ?S� values of insertion are modulated by a change of counterion and solvent.

Single insertion of α-olefins into the M-C bond of metallaaziridinium ion pairs: Assessing the counterion–solvent interplay

245th National Meeting (2013)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.