Synthesis and Structure of Group 4 Symmetric AmidinateComplexes and Their Reactivity in the Polymerization of α-Olefins.

The steric properties of variousnitrogen substituents on amidineswere tuned in order to obtain group 4 mono- and bis(amidinate) dimethylamidoor chloride complexes. The amidinate dimethylamido and chloride complexeswere prepared, and their solid-state as well as their solution-statestructures were studied. After the activation by MAO, these complexeswere tested in the polymerization of propylene and ethylene. A noticeableinfluence of the amidine carbon and nitrogen substituents on the activityof the catalyst and properties of the obtained polymer was observed.Further, a plausible mechanism for the ethylene polymerization processis presented taking into account a combination of ESR-C60and MALDI-TOF experiments, shedding light on the nature of the catalyticspecies. [ABSTRACT FROM AUTHOR]