DFT Studies on the Mechanisms of Carboamination/Diamination of Unactivated Alkenes Mediated by Pd(IV) Intermediates.

Abstract

Density functional theory (DFT) calculations have been employed to investigate the mechanism of carboamination and diamination of unactivated alkenes mediated by Pd(IV) intermediates. Both reactions share a common Pd(IV) intermediate, serving as the starting point for either the carboamination or the diamination pathway. The formation of this Pd(IV) intermediate encompasses a transition state that substantially impacts the turnover frequency (TOF) of catalytic cycles, with an apparent activation free-energy barrier of 26.1 kcal mol-1. Carboamination of unactivated alkenes proceeds through the coordination of a toluene molecule, C-H activation, inner reductive elimination, and the separation of the carboamination product from this intermediate, while diamination of unactivated alkenes involves the formation of the ion nucleophile, SN2 attack, and the separation of the diamination product. A comparison of the free-energy profiles for carboamination and diamination of unactivated alkenes can elucidate the origin of the chemoselectivity, and Bader's atoms in molecules (AIM) wave function analyses have been performed to analyze the contributions of the outer C-N bonding in the diamination process.