Thionitrosyl complexes of molybdenum, rhenium, and osmium

Abstract

The molybdenum nitrido-complexes [MoN(S₂CNR₂)₃] react with elemental sulphur or propylene sulphide to give the thionitrosyl complexes [Mo(NS)(S₂CNR₂)₃] in high yield. The rhenium nitrido-complexes [ReX₂N(PR₃)₃](PR₃= PMe₂Ph, PEt₂Ph, or PMePh₂; X = Cl or Br) react with half an equivalent of S₂Cl₂ to give the pink thionitrosyl complexes [ReCl(X)(NS)(PR₃)₃] in yields of 60–70%. Use of an excess of S₂Cl₂ gives the purple complexes [ReCl₂X(NS)(PR₃)₂] in good yields. The five-co-ordinate nitrido-complexes [ReCl₂N(PRPh₂)₂](R = Ph or Prⁿ) also give [ReCl₃(NS)(PRPh₂)₂] on reaction with half an equivalent of S₂Cl₂. The osmium nitrido-complexes [OsX₃NL₂][L = AsPh₃, PMe₂Ph, ½ bipy (2,2′-bipyridyl), or py (pyridine); X = Cl or Br] react analogously with S₂Cl₂ to give [OsClX₂(NS)L₂]. ν(N–S) appears in the i.r. spectra in the range 1 120–1 280 cm^–1, and the ¹H n.m.r. spectra of the diamagnetic complexes show the phosphines to be mer in [ReCl₂(NS)(PR₃)₃] and trans in [OsCl₃(NS)(PMe₂Ph)₂]. Treatment of the thionitrosyls with tertiary phosphines regenerates the parent nitrido-complexes in high yields.