Preparation of cationic dinuclear hydride complexes of ruthenium, rhodium,and iridium with bridging thiolate ligands and their reactions with nitrosobenzene

A series of cationic dinuclear hydride complexes with bridging thiolato lig ands [Cp*MH(mu-SPri)(2)MCp*] [OTf] (4, M = Ru; 6a, M = Rh; 7a, M = Ir; Cp* = eta(5)-C5Me5, OTf = OSO2CS) were synthesized by treatment of the correspo nding chloro complexes [Cp*RuCl(mu-SPri)(2)Ru(OH2)Cp*][OTf] (1) or [Cp*M(mu -Cl)(mu-SPri)(2)MCp*] [OTf] (2, M = Rh; 3, M = Ir) with HSiEt3. The dirhodi um and diiridium complexes 6 and 7 have been shown to possess a bridging hy dride ligand by crystallographic analysis, while the diruthenium complex 4 is proposed to have a terminal hydride ligand that undergoes facile migrati on between the two ruthenium centers in solution. Complexes 4, 6a, and 7a r eacted with nitrosobenzene to give the paramagnetic dinuclear nitrosobenzen e complexes [Cp*M(mu-PhNO)(mu-sPr(i))(2)MCp*](+) (M = Ru, Rh, Ir) along wit h azoxybenzene. The molecular structures of the three nitrosobenzene comple xes have been determined by X-ray diffraction study to reveal that in each case nitrosobenzene acts as a mu-eta(1):eta(1)-N,O ligand. Judging from the molecular structures and the ESR spectra, the unpaired electron is conside red to be located mainly on the nitrosobenzene ligand, at least in the diru thenium and dirhodium complexes. On the other hand, complex 2 reacted with nitrosobenzene to give the incomplete cubane-type trinuclear cluster [(Cp"R h)(3)(mu-Cl)(2)(mu(3)-S)(mu-SPri)](+), whose molecular structure has also b een determined crystallographically.