A Diruthenium μ-Carbido Complex That Shows Singlet-Carbene-like Reactivity

Abstract

Low-temperature deprotonation of the cationic μ-methylidyne complex [(Cp*Ru)2(μ-NPh)(μ-CH)][BF4] (Cp* = η(5)-C5Me5) with KN(SiMe3)2 affords a thermally unstable μ-carbido complex [(Cp*Ru)2(μ-NPh)(μ-C)] (2), as evidenced by trapping experiments with elemental S or Se and (13)C NMR spectroscopic observation. The reactivity of 2 toward CO2, Ph2S(+)CH2(-), EtOH, and an intramolecular C-H bond indicates that the μ-carbido carbon in 2 has an ambiphilic (nucleophilic and electrophilic) nature consistent with the formulation of 2 as the first example of a transition-metal-substituted singlet carbene. DFT study suggests that the Ru substituents in 2 are stronger σ-donor and weaker π-donor to the carbene center than amino substituents in N-heterocyclic carbenes.