Preparation and properties of complexes of osmium(II) with carbonyl, nitrosyl, organic cyanide and organic isocyanide ligands

Abstract

The new complexes [OsX₂(Y)(PR₃)₃], [OsX₂(Y)₂(PR₃)₂], and [Os₂X₃(PR₃)₆]⁺(X = Cl or Br; Y = CO, MeNC, PhNC, MeCN or PhCN; PR₃= tertiary phosphine or AsMe₂Ph) have been prepared by the zinc reduction of [OsX₃(PR₃)₃] in presence of Y. Under these conditions, nitrogen oxide gives the complexes [OsCl₂(NO₂)(NO)(PMe₂Ph)₂] and [OsCl(NO₂)(NO)(PMe₂Ph)₃]⁺. The ¹H and ³¹P n.m.r. spectra of the complexes are discussed and used in conjunction with i.r. data to assign configurations. The osmium–chlorine stretching frequencies of the complexes are recorded and discussed. Reactions of [OsX₂(Y)(PR₃)₃] and [OsX₂(Y)₂(PR₃)₂] with dichlorine, tertiary phosphine, and carbon monoxide are described. The compound [OsCl₂(PMe₂Ph)₃MeNC]Cl results from dichlorine oxidation of [OsCl₂(PMe₂Ph)₃MeNC]. The bonding characteristics of the ligands Y are compared with those of dinitrogen.