Reactivity of new osmium dihydrides with arenediazonium cations: Preparation and properties of bis(aryldiazene) and mono(aryldiazenido) complexes. A comparison with analogous iron and ruthenium derivatives

Hydride complexes [OsH2L4] [L = P(OEt)3 or PPh(OEt)2] were prepared. Their reactions with arenediazonium cations led to the synthesis of [Os(RN=NH)2L4] [BPh4]2 and [OsH(RN=NH)L4]BPh4(R = Ph, 4-MeC6H4, or 4-MeOC6H4) complexes which were characterized by 1H and 31P n.m.r. data (with 15N isotopic substitution). The compounds [Os(4-MeC6H4N=NH)(4-MeC6H4NC)L 4][BPh4]2 were also prepared. The reaction of the bis(aryldiazene) derivatives with NEt3 led to new five-co-ordinate aryldiazenido complexes [Os(RN2)L4]BPh4(R = Ph or 4-MeC6H4). Protonation of the diazenido compounds with CF3CO2H and HBF4 gave the six-co-ordinate mono(diazene) [Os(CF3CO2)(RN=NH)L4]BPh4 and the five-co-ordinate [Os(RN=NH)L4]BPh4 (R = 4-MeC6H4) derivatives, respectively. Infrared and 1H and 31P n.m.r. data for these complexes are reported