Ab initio study of ethylene insertion into M–C bonds of alkylamidinates complexes of group IV ({R′NCRNR′}2MCH3+, M=Zr, Ti, R=H, Ph and R′=H, SiMe3)

Alkylamidinate complexes have been recently reported to be useful catalysts for olefin polymerisation as an alternative to metallocene systems. The present work reports theoretical calculations performed at DFT level for ethylene insertion reactions in zirconium and titanium alkylamidinate compounds with variable structural complexity. The energy barriers obtained for these reactions show that these systems can be considered as efficient olefin polymerisation catalysts, but less active than their metallocene counterparts, in agreement with experimental findings. A comparison between alkylamidinates of Ti and Zr is also provided.