Alkane and alkene oxidation reactions catalyzed by nickel(II) complexes: Effect of ligand factors

Abstract

Targeting selective hydroxylation under mild conditions of saturated hydrocarbons has become a challenging and exciting scientific area that has drawn larger attention in recent years because high temperatures and high pressures are required for industrial hydroxylation processes. In contrast, enzymes such as cytochrome P450, methane monooxygenases, and bleomycin catalyze the selective hydroxylation reactions using molecular oxygen as green oxidant under mild conditions. Inspired by these natural enzymes, noteworthy attempts have been made to replicate their functional features and several bio-mimetic and bio-inspired metal complexes have been investigated as catalysts for the hydroxylation of alkanes. Although iron complexes are considered as one of the most proficient transition metal catalysts for this industrially important reaction, in recent years nickel complexes have attracted greater attention as catalysts for alkane hydroxylation, epoxidation and benzene oxidation reactions. The objective of this review is to enumerate the versatile uses of nickel(II) complexes as catalysts for various oxidation reactions in the last few years. The review will summarize the important role of ligand stereoelectronic factors in dictating the selectivity and efficiency of the nickel(II) catalyzed CH and CC bond oxidation reactions.