Snapshots of a Reversible Metal–Ligand Two‐Electron Transfer Step Involving Compounds Related by Multiple Types of Isomerism

Abstract

AbstractAn unusual and very fast equilibrium between two isomers, [(cod)Rh–I{(bpa – 2H)0}IrI(cod)][rlhar2][(cod)RhI{(bpa – 2H)2–}IrI(cod)], which simultaneously display multiple types of isomerism: ligand–metal redox (electromerism), linkage, bond‐stretch and ring‐slippage isomerism, has been studied by NMR spectroscopy and DFT calculations. Both isomers have been isolated by making rational use of their thermodynamic parameters (ΔH° = +1.93 kcal mol–1; ΔS° = +7.8 cal mol–1 K–1), and have been characterized by X‐ray diffraction methods. The equilibrium that involves a two‐electron exchange between a redox noninnocent ligand, which transforms from a deprotonated amido form into an imine, and a metal that is reduced, could elucidate a thus far obscure step in the oxidative dehydrogenation of amines to imines.