Hydrolysis of Coordinated Diazoalkanes To Yield Side-On 1,2-Diazene Derivatives

Diazoalkane complexes [Ru­(η⁵-C₅Me₅)­(N₂CAr1Ar2)­(PPh₃)­{P­(OR)₃}]­BPh₄ [R = Me (<b>1</b>), Et (<b>2</b>); Ar1 = Ar2 = Ph (<b>a</b>); Ar1 = Ph, Ar2 = <i>p</i>-tolyl (<b>b</b>); Ar1Ar2 = C₁₂H₈ (<b>c</b>)] were prepared by allowing chloro complexes RuCl­(η⁵-C₅Me₅)­(PPh₃)­[P­(OR)₃] to react with diazoalkane Ar1Ar2CN₂ in ethanol. The treatment of compounds <b>1</b> and <b>2</b> with H₂O afforded 1,2-diazene derivatives [Ru­(η⁵-C₅Me₅)­(η²-NHNH)­(PPh₃)­{P­(OR)₃}]­BPh₄ (<b>3</b> and <b>4</b>) and ketone Ar1Ar2CO. A reaction path involving nucleophilic attack by H₂O on the coordinated diazoalkane is proposed. The complexes were characterized spectroscopically (IR and NMR) and by X-ray crystal structure determination of [Ru­(η⁵-C₅Me₅)­(η²-NHNH)­(PPh₃)­{P­(OMe)₃}]­BPh₄ (<b>3</b>)