SYNTHESIS AND CRYSTAL-STRUCTURES OF [PPH4][MN(BUTNC-(O)NBUT)CL2] (M = RU OR OS) - A NEW REACTION OF TERT-BUTYL ISOCYANATE - SYNTHESIS OF W[BUTNC(O)NBUT]2(NHBUT)2

The interaction of the tetraphenylphosphonium salts of the ruthenium- and osmium-(VI) anions [RuO2Cl3]-, [RuO2Cl4]2- and [OsO2Cl4]2- with excess of tert-butyl isocyanate in acetonitrile forms the salts of the anions [MN{Bu(t)NC(O)NBu(t)}Cl2]-, M = Ru or Os. X-Ray diffraction studies have shown the anions to have distorted square-pyramidal geometry with the nitrido groups in axial positions. The metal nitrido groups have been shown to arise by C-N bond cleavage of unisolated tert-butylimido intermediates accompanied by cycloelimination of Me2C = CH2 and HCl. Similar reactions using other aryl and alkyl isocyanates gave intractable products. The compound W[Bu(t)NC(O)NBu(t)]2-(NHBu(t))2 is formed on reaction of W(NBu(t))2(NHBu(t))2 with Bu(t)NCO.