Reaction of isocyanides with iminophosphorane-based carbene ligands: Synthesis of unprecedented ketenimine–ruthenium complexes

The Rudouble bond; length as m-dashC bond of the bis(iminophosphorano)methandiide-based ruthenium(II) carbene complexes [Ru(η6-p-cymene)(κ2-C,N-C[P{double bond; length as m-dashNP(double bond; length as m-dashO)(OR)2}Ph2]2)] (R = Et (1), Ph (2)) undergoes a C–C coupling process with isocyanides to afford ketenimine derivatives [Ru(η6-p-cymene)(κ3-C,C,N-C(Cdouble bond; length as m-dashNR′)[P{double bond; length as m-dashNP(double bond; length as m-dashO)(OR)2}Ph2]2)] (R = Et, R′ = Bz (3a), 2,6-C6H3Me2 (3b), Cy (3c); R = Ph, R′ = Bz (4a), 2,6-C6H3Me2 (4b), Cy (4c)). Compounds 3–4a–c represent the first examples of ketenimine–ruthenium complexes reported to date. Protonation of 3–4a with HBF4 · Et2O takes place selectively at the ketenimine nitrogen atom yielding the cationic derivatives [Ru(η6-p-cymene)(κ3-C,C,N-C(CNHBz)[P{double bond; length as m-dashNP(double bond; length as m-dashO)(OR)2}Ph2]2)][BF4] (R = Et (5a), Ph (6a)).