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(CH3NNH)(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).

The preparation of hydrazine complexes of ruthenium and osmium stabilised by the p-cymene fragment [MCl(η6-p-cymene)L]+ is described. Oxidation with Pb(OAc)4 at −30 °C of [OsCl(η6-p-cymene)(CH3NHNH2)L]BPh4, leading to the methyldiazenido derivative [Os(CH3N2)(η6-p-cymene)L]BPh4, is also reported.Figure optionsDownload as PowerPoint slideHighlights
► Facile synthesis of half-sandwich hydrazine complexes of Ru and Os.
► Oxidation with Pb(OAc)4 leads to both Ru-acetate and Os-methyldiazenido complexes.
► Reaction of Os-methyldiazenido complexes with HCl affords methyldiazene cations.