Catalytic reactions and electrochemical studies of a Mo-dioxo system supported by bulky pincer ligands

by Tran, Randy; Sanders, Miranda L.; Kilyanek, Stefan M.

Molybdenum dioxo species supported by sterically demanding ligand environments were observed to afford relatively slow deoxydehydration (DODH) reactions of vicinal diols. These bulky ligands altered product distributions and increased alkene yields for a variety of diols. Electrochem. studies were performed on these DODH catalysts to gain a fundamental understanding of the proton transfer and electron transfer processes that are involved in converting the molybdenum-dioxo fragment into an active mono-oxo species. The elementary steps of this reaction were found to be coupled together in a proton coupled electron transfer (PCET) process. The catalysts were screened against a variety of Bronsted acids within a pKa window of ~9-32 in THF. Electrochem. studies of the molybdenum catalyst suggests a PTET mechanism. Future studies involve the further rational design of ligand environments to directly access the reduced DODH active species with min. energy input as an efficient and alternative method to generate industrially relevant chem. precursors.