Abstract
A nickel catalyst was modeled with ligand L^2^, [NH = CHβCH = CHβO]^β^, which should have potential use as a syndiotactic polyolefin catalyst, and the reaction mechanism was studied by theoretical calculations using the density functional method at the B3LYP/ LANL2MB level. The mechanism involves the formation of the intermediate [NiL^2^Me]^+^, in which the metal occupies a Tβshaped geometry. This intermediate has two possible structures with the methyl group trans either to the oxygen or to the nitrogen atom of L^2^. The results show that both structures can lead to the desired product via similar reaction paths, A and B. Thus, the polymerization could be considered as taking place either with the alkyl group occupying the position trans to the NiβO or trans to the NiβN bond in the catalyst. The polymerization process thus favors the catalysis of syndiotactic polyolefins. The syndiotactic synthesis effects could also be enhanced by variations in the ligand subβstituents. From energy considerations, we can conclude that it is more favorable for the methyl group to occupy the transβO position to form a complex than to occupy the transβN position. From bond length considerations, it is also more favoured for ethene to occupy the transβO position than to occupy the transβN position.