Novel synthetic routes to disulphur and disulphur monoxide ligands: nucleophilic attack at co-ordinated imino-oxo-λ4-sulphanes

Abstract

The reactions of [OsCl(NO)(C₂H₄)(PPh₃)₂] and [IrCl(CO)(PPh₃)₂] with oxo-4-tosylimino-λ⁴-sulphane (4-MeC₆H₄SO₂NSO) lead quantitatively to the adducts [{ML}Cl(PPh₃)₂(4-Me-C₆H₄SO₂NSO)][{ML}= Os(NO) or Ir(CO)] which in turn are hydrolysed to the corresponding sulphur dioxide complexes [{ML}Cl(PPh₃)₂(SO₂)]. The iridium compound [IrCl(CO)(PPh₃)₂(4-Me-C₆H₄SO₂NSO)] reacts cleanly with hydrogen sulphide to provide the disulphur monoxide complex [IrCl(CO)(PPh₃)₂(S₂O)] whilst [OsCl(NO)(PPh₃)₂(4-MeC₆H₄SO₂NSO)] with hydrosulphide leads to the disulphur complex [OsCl(NO)(PPh₃)₂(S₂)] which may be oxidised to the corresponding S₂O complex [OsCl(NO)(PPh₃)₂(S₂O)] with 3-chloroperbenzoic acid. Alternatively, [OsCl(NO)(PPh₃)₂-(S₂)] is accessible via the reaction of [OsCl(NO)(PPh₃)₃] with cyclo-octasulphur.