Voltammetric Investigations of Low-Coordinate Manganese As an Electrocatalyst for Organic Coupling and Functionalization

Abstract

Earth-abundant, first row, low coordinate transition metal complexes are considered promising candidates for the electrocatalysis of many organic reactions. The use of transition metal catalysts is no stranger to the field of synthetic organic chemistry; however, many of the existing catalysts require the use of rare and expensive metals such as platinum, palladium, ruthenium, and iridium. In this study, we seek to identify and understand the mechanism by which an Mn(I) complex may act as an electrocatalyst for simple organic coupling and C-H functionalization reactions, beginning with the radicalization of benzyl bromide and benzyl chloride as representative organic halide substrates. The careful design and evaluation of this manganese complex has the potential to offer an effective non-toxic 3d metal electrocatalyst, provided that common transition metal behaviors, such as disproportionation or carbon-metal bond formation, are avoided. Initial characterization of the complex by cyclic voltammetry (CV) demonstrates general reversibility of the catalyst, while additions of benzyl halide exhibit the execution of the electron transfer and catalytic step. Electrochemical simulations run in parallel with CV experiments provide supplementary guidance into the relationship between the substrate and catalyst. Additional studies conducted using bulk electrolysis, mass spectrometry, nuclear magnetic resonance, and density functional theory (DFT) calculation will help to further characterize the mechanism and supporting details. Elucidation of the catalytic mechanism will allow us to use this electrocatalyst in a series of synthetic organic conditions and aid in our advancement toward sustainable organometallic catalysis.