Synthesis and reactivity of dinuclear Cp*Ru tert-butylamido and cyclometallated Bis(trimethylsilyl)amido complexes

• Reactions of [Cp*Ru(μ3-Cl)]4 with LiNHtBu and NaN(SiMe3)2.
• Synthesis of dinuclear amido, imido, and cyclometallated silyamido complexes.
• Reversible C–H reductive coupling in the cyclometallated complex.

Treatment of [Cp*Ru(μ3-Cl)]4 with 4 equiv of LiNHtBu in THF produces the dimeric tert-butylamido complex [Cp*Ru(μ-NHtBu)]2 (1b) in 85% yield. Complex 1b reacts with Ph2SCH2 and CNtBu to give the imido methylene complex (Cp*Ru)2(μ-NtBu)(μ-CH2) (2b) and the bis(amido) bis(isocyanide) complex [Cp*Ru(CNtBu)(μ-NHtBu)]2 (3b), respectively. The reaction of [Cp*Ru(μ3-Cl)]4 with 4 equiv of NaN(SiMe3)2 proceeds via double C–H activation of a SiMe group to give the cyclometallated silylamido complex (Cp*Ru)2(μ-H)(μ-HCSiMe2NSiMe3) (4) in 91% yield. Single-crystal X-ray analysis and low-temperature 1H and 13C NMR spectroscopy for 4 reveal the amido-carbene formulation of the cyclometallated ligand. Variable-temperature NMR analysis for 4 reveals a rapid exchange of the hydride and carbene protons and indicates a reversible C–H reductive coupling between the silylcarbene and the hydride moieties, which has been reasonably modeled by DFT calculations.

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