Exploring ethylene insertion reaction mechanism in nickel complexes: a comparative study by the reaction force and reaction electronic flux in molecular and SiO2-supported catalysts.

Abstract

This study investigates the ethylene insertion reaction mechanism for polymerization catalysis, aiming to discern differences between Ni-α-imine ketone-type catalyst and their SiO2-supported counterpart. The reaction force analysis unveils a more intricate mechanism with SiO2 support, shedding light on unexplored factors and elucidating the observed lower catalytic activity. Furthermore, reactivity indexes suggest earlier ethylene activation in the supported catalyst, potentially enhancing overall selectivity. Finally, the reaction electronic flux analysis provides detailed insights into the electronic activity at each step of the reaction mechanism. In sum, this study offers a comprehensive understanding of the ethylene insertion reaction mechanism in both molecular and supported catalysts, underscoring the pivotal role of structural and electronic factors in catalytic processes. Density functional theory (DFT) calculations were conducted using the ωB97XD functional and the 6-31 + G(d,p) basis sets with Gaussian16 software. Computational techniques utilized in this study encompassed the IRC method, reaction force analysis, and evaluation of electronic descriptors such as electronic chemical potential, molecular hardness, and electrophilicity reactivity indexes. Additionally, reaction electronic flux analysis was employed to investigate electronic activity along the reaction coordinate.