THE FORMATION OF METAL HYDRIDO COMPLEXES VIA PROTONATION OF COORDINATED ETHYLENE - RELATIVE RATES OF PROTONATION OF COORDINATED ETHYLENE AND METAL

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-degrees-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 beta-hydrogen migration from the derived ethyl ligand to the metal.