Influence of phosphine (pincer) ligands on the transition metal hydrides reactivity

Transition-metal hydride complexes are plenteous in organometallic chemistry. The reactivity of metal hydrides is determined by three possible pathways of M-H bond cleavage: homolytic cleavage yielding a hydrogen radical (H-center dot), and heterolytic cleavage generating either a proton (H+) or hydride (H-). These steps, especially the proton and hydride transfer, are critical in a vast array of stoichiometric and catalytic transformations. Many late transition metal hydrides are supported by phosphine ligands, which allow tuning the electronic and steric properties at a metal center in a systematic and predictable way. In this non-exhaustive review we attempt to trace the influence of phosphines properties on the reactivity of transition metal hydrides in topical stoichiometric and catalytic processes highlighting the reactions' mechanisms and the role of hydrogen bonding interactions in the intermediates of hydrogen transfer reactions. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

Transition-metal hydride complexes are abundant in organometallic chemistry, with their reactivity determined by homolytic and heterolytic cleavage of M-H bonds. Late transition metal hydrides are often supported by phosphine ligands, allowing for systematic tuning of electronic and steric properties at the metal center. The influence of phosphine properties on the reactivity of transition metal hydrides in stoichiometric and catalytic processes is traced in this review, highlighting the role of hydrogen bonding interactions in hydrogen transfer reactions.