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 [OsH<inf>2</inf>L<inf>4</inf>] [L = P(OEt)<inf>3</inf> or PPh(OEt)<inf>2</inf>] were prepared. Their reactions with arenediazonium cations led to the synthesis of [Os(RN=NH)<inf>2</inf>L<inf>4</inf>] [BPh<inf>4</inf>]<inf>2</inf> and [OsH(RN=NH)L<inf>4</inf>]BPh<inf>4</inf>(R = Ph, 4-MeC<inf>6</inf>H<inf>4</inf>, or 4-MeOC<inf>6</inf>H<inf>4</inf>) complexes which were characterized by ¹H and ³¹P n.m.r. data (with ¹⁵N isotopic substitution). The compounds [Os(4-MeC<inf>6</inf>H<inf>4</inf>N=NH)(4-MeC<inf>6</inf>H<inf>4</inf>NC)L <inf>4</inf>][BPh<inf>4</inf>]<inf>2</inf> were also prepared. The reaction of the bis(aryldiazene) derivatives with NEt<inf>3</inf> led to new five-co-ordinate aryldiazenido complexes [Os(RN<inf>2</inf>)L<inf>4</inf>]BPh<inf>4</inf>(R = Ph or 4-MeC<inf>6</inf>H<inf>4</inf>). Protonation of the diazenido compounds with CF<inf>3</inf>CO<inf>2</inf>H and HBF<inf>4</inf> gave the six-co-ordinate mono(diazene) [Os(CF<inf>3</inf>CO<inf>2</inf>)(RN=NH)L<inf>4</inf>]BPh<inf>4</inf> and the five-co-ordinate [Os(RN=NH)L<inf>4</inf>]BPh<inf>4</inf> (R = 4-MeC<inf>6</inf>H<inf>4</inf>) derivatives, respectively. Infrared and ¹H and ³¹P n.m.r. data for these complexes are reported.