Dihydrogen and hydrido complexes via hydrogen addition to d6 five-co-ordinate complexes of ruthenium and osmium with 1,2-bis(dicyclohexylphosphino)ethane

Abstract

The dihydrogen complexes [MX(η²-H₂)(dcpe)₂]BPh₄[dcpe = 1,2-bis(dicyclohexylphosphino)ethane; M = Ru, X = H or Cl; M = Os, X = Cl] were prepared by reaction of molecular hydrogen with the five-co-ordinate complexes [MX(dcpe)₂BPh₄, or by protonation of the hydrides [MH(X)(dcpe)₂]. The same synthetic procedures yielded [OsH₃(dcpe)₂]BPh₄, for which a classical trihydride seven-co-ordinate structure is proposed. The compounds have been characterized by variable-temperature ¹H and ³¹P-{¹H} NMR spectra and T₁ measurements. The reaction of molecular hydrogen with the complexes cis-[MCl₂(dcpe)₂] to yield trans-[MH(Cl)(dcpe)₂] and cis-[MH₂(dcpe)₂] is also discussed.