Preparation and reactivity of p-cymene complexes of ruthenium and osmium incorporating 1,3-triazenide ligands

p-Cymene complexes MCl₂(η⁶-p-cymene)L M = Ru, Os; L = P(OEt)₃, PPh(OEt)₂, (CH₃)₃CNC] were prepared by allowing MCl(μ-Cl)(η⁶-p-cymene)]₂ to react with phosphites or tert-butyl isocyanide. Treatment of MCl₂(η⁶-p-cymene)L complexes with 1,3-ArNNN(H)Ar triazene and an excess of NEt₃ gave the cationic triazenide derivatives M(η²-1,3-ArNNNAr)(η⁶-p-cymene)L]BPh₄ (Ar = Ph, p-tolyl). Neutral triazenide complexes MCl(η²-1,3-ArNNNAr)(η⁶-p-cymene) (M = Ru, Os) were also prepared by allowing MCl(μ-Cl)(η⁶-p-cymene)]₂ to react with 1,3-diaryltriazene in the presence of triethylamine. p-Cymene complexes MCl₂(η⁶-p-cymene)L reacted with equimolar amounts of 1,3-ArNNN(H)Ar triazene to give both triazenide complexes M(η²-1,3-ArNNNAr)(η⁶-p-cymene)L]BPh₄ and amine derivatives MCl(ArNH₂)(η⁶-p-cymene)L]BPh₄. A reaction path for the formation of the amine complex is also reported. The complexes were characterised by spectroscopy and X-ray crystallography of RuCl₂(η⁶-p-cymene)PPh(OEt)₂] and Ru(η²-1,3-p-tolyl-NNN-p-tolyl)(η⁶-p-cymene){CNC(CH₃)₃}]BPh₄. Selected triazenide complexes were studied as catalysts in the hydrogenation of 2-cyclohexen-1-one and cinnamaldehyde.