Formation of a Half-Sandwich Triscarbene Ruthenium Complex: Oxidative Coupling of 2,7-Nonadiyne Mediated by [RuCp(IPrⁱ)(CH₃CN)₂]⁺ (IPrⁱ = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene)

[RuCp(IPri)(CH3CN)2]PF6, prepared by the reaction of [RuCp(CH3CN)3]PF6 with 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (IPri), promotes the oxidative coupling of 2,7-nonadiyne to afford the novel cationic half-sandwich triscarbene complex [RuCp(IPri)(C2(CH3)2C2(CH2)3)]PF6. This compound has been characterized by X-ray crystallography. At elevated temperature in the presence of trace amounts of water the triscarbene undergoes a formal 1,2 hydrogen shift to give the butadienyl carbene complex [RuCp(IPri)(C(CH3)-C(CH2)3C-η2-CHCH2)]PF6.