Syntheses, structures, reactions, and vibrational spectra of complexes containing osmium–gold bonds: trinuclear osmium and related complexes

Abstract

Complexes of the general formula [Os3(CO)10(AuPPh3)X](X = Cl, Br, I, or SCN) and [Os3(CO)10(AuPAr3)Cl](Ar = C6H4Me) have been prepared from Os3(CO)12 and [Au(PAr3)X]. Molecular-weight studies on these complexes, both in solution and by mass spectrometry, as well as vibrational spectral work, indicate that they contain three osmium atoms, and this is confirmed by a preliminary X-ray crystallographic study for [Os3(CO)10(AuPPh3)X](X = Cl or Br), which shows each complex to contain a cluster of one gold and three osmium atoms. The thiocyanate complex can be converted into one containing two gold and three osmium atoms. Other products have also been isolated, including [Os3(CO)12–x(PPh3)x], (x = 1–3), and [Os(CO)2(PPh3)2X2](X = Cl, Br, or I). The former are also believed to be trinuclear, whereas the latter are monomers with cis-carbonyl groups and cis-halogen groups. The i.r. and Raman spectra of all the complexes have been recorded in the ranges 2200–1900 and 850–70 cm–1, both in the solid state and where possible also in solution, and assignments for many of the fundamentals are presented.Attempts to prepare analogous silver and copper complexes and ruthenium–gold complexes were unsuccessful.