Synthesis, characterization, and multi-​proton​/multi-​electron chemistry of molybdenum-​quinoid complexes supported by a non-​innocent ligand

Abstract

Incorporation of redox non-innocent ligands as well as pendant acid/base moieties has proven effective as a method for overcoming the propensity for earth-abundant transition metals to preferentially access single-electron chem. and facilitate efficient multi-proton, multi-electron activation of small mols. such as dioxygen. A series of molybdenum-quionoid complexes supported by a non-innocent ligand have been synthesized and characterized demonstrating both hydrogen atom and proton and electron transfer chem. spanning a total of four electrons and two protons. Five different protonation/oxidn. state combinations were isolated varying from Mo(0)-catechol to Mo(II)-quinone. Substrate-based multi-proton, multi-electron reactivity was demonstrated through redn. of dioxygen to water, and mechanistic insight gained via substituting the protons for other Lewis-acidic moieties will also be presented.