ACTIVATION AND CLEAVAGE OF THE C-S BOND IN NB-STBU COMPLEXES - SYNTHESES AND STRUCTURAL CHARACTERIZATIONS OF THE TETRAHEDRAL AND TRIGONAL BIPYRAMIDAL [PH4P][NBV(S)2(TBUS)2] AND [ET4N][NBV(S)(TBUS)4] COMPLEXES

The trigonal bipyramidal [NbV(S)(tBuS)4]- anion of II is obtained by the reaction of NbCl5 with NaS(t)Bu in CH3CN solution. This anion in solution decomposes to the tetrahedral [NbV(S)2(tBuS)2]- anion of I. The detection of isobutene and isobutane among the reaction byproducts indicates that C S bond cleavage in the (t)BuS- ligand occurs either by a (t)BuS -assisted deprotonation of a (t)Bu+ carbonium ion or by a homolytic bond cleavage reaction.