A RuII–N-heterocyclic carbene (NHC) complex from metal–metal singly bonded diruthenium(I) precursor: Synthesis, structure and catalytic evaluation

A mononuclear Ru(II)–N-heterocyclic carbene (NHC) complex [RuII(CO)2(κ2C,N-BIN)(H2O)Br][OTf] (OTf = trifluoromethane sulphonate) (1) has been synthesized in high-yield by the oxidative cleavage of the metal–metal singly-bonded diruthenium(I) precursor [Ru2(CO)4(CH3CN)6(OTf)2] with 1,8-naphthyridine functionalized NHC precursor 1-benzyl-3-(5,7-dimethyl-1,8-naphthyrid-2-yl)imidazolium bromide (BIN·HBr) at room temperature. Compound 1 catalyzes transfer hydrogenation of ketones to alcohols, and carbene-transfer from ethyl diazoacetate to a variety of substrates. It is shown to be an excellent catalyst for the insertion of carbene into the O–H and N–H bonds of alcohols and amines.

Oxidative addition of the imidazolium C2–H to a metal–metal singly-bonded diruthenium(I) precursor [Ru2(CO)4(CH3CN)6(OTf)2] affords a RuII–NHC complex at room temperature in high-yield.Figure optionsDownload as PowerPoint slideResearch highlights
► Metal-metal bonded diruthenium(I) precursor for the high-yield synthesis of RuII–NHC complex.
► Oxidative cleavage of the Ru–Ru bond by imidazolium C2–H bond.
► Ru-NHC complex as carbene-transfer catalyst from EDA.