The formation of metal hydrido complexes via protonation of coordinated ethylene: relative rates of protonation of coordinated ethylene and metal

Abstract

The formation of [MH(C₂H₄)₂(dppe)₂]⁺ from the reaction of trans-[M(C₂H₄)₂(dppe)₂] with HX (M = Mo or W, dppe = Ph₂PCH₂CH₂PPh₂, X = Cl or Br) has been studied in tetrahydrofuran at 25 °C by stopped-flow spectrophotometry, and shown to occur by two pathways: the slow direct protonation of the metal, and the rapid protonation of the ethylene ligand followed by relatively slow intramolecular β-hydrogen migration from the derived ethyl ligand to the metal.