Preparation and reactivity of half-sandwich hydrazine complexes of ruthenium and osmium

Hydrazine complexes [MCl(η6-p-cymene)(RNHNH2)L]BPh4 (1–6) [M = Ru, Os; R = H, Me, Ph; L = P(OEt)3, PPh(OEt)2, PPh2OEt] were prepared by allowing dichloro complexes MCl2(η6-p-cymene)L to react with hydrazines RNHNH2 in the presence of NaBPh4. Treatment of ruthenium complexes [RuCl(η6-p-cymene)(RNHNH2)L]BPh4 with Pb(OAc)4 led to acetate complex [Ru(κ2–O2CCH3)(η6-p-cymene)L]BPh4 (7). Instead, the reaction of osmium derivatives [OsCl(η6-p-cymene)(CH3NHNH2)L]BPh4 with Pb(OAc)4 afforded the methyldiazenido complex [Os(CH3N2)(η6-p-cymene)L}]BPh4 (8). Treatment with HCl of this diazenido complex 8 led to the methyldiazene cation [OsCl(CH3Ndouble bond; length as m-dashNH)(η6-p-cymene)L}]+ (9+). The complexes were characterised spectroscopically and by X-ray crystal structure determination of [OsCl(η6-p-cymene)(PhNHNH2){PPh(OEt)2}]BPh4 (6b) and [Ru(κ2–O2CCH3)(η6-p-cymene){PPh(OEt)2}]BPh4 (7b).