Experimental Electrochemical Potentials of Nickel Complexes

Abstract Nickel-catalyzed cross-coupling and photoredox catalytic reactions has found widespread utilities in organic synthesis. Redox processes are key intermediate steps in many catalytic cycles. As a result, it is pertinent to measure and document the redox potentials of various nickel species as precatalysts, catalysts, and intermediates. The redox potentials of a transition-metal complex are governed by its oxidation state, ligand, and the solvent environment. This article tabulates experimentally measured redox potentials of nickel complexes supported on common ligands under various conditions. This review article serves as a versatile tool to help synthetic organic and organometallic chemists evaluate the feasibility and kinetics of redox events occurring at the nickel center, when designing catalytic reactions and preparing nickel complexes. 1 Introduction 1.1 Scope 1.2 Measurement of Formal Redox Potentials 1.3 Redox Potentials in Nonaqueous Solution 2 Redox Potentials of Nickel Complexes 2.1 Redox Potentials of (Phosphine)Ni Complexes 2.2 Redox Potentials of (Nitrogen)Ni Complexes 2.3 Redox Potentials of (NHC)Ni Complexes