Reaction of 16-Electron Ruthenium and Iridium Amide Complexes with Acidic Alcohols: Intramolecular C−H Bond Activation and the Isolation of Cyclometalated Complexes

Abstract

The 16-electron transition metal amide complexes, Cp*M[κ2(N,N‘)-(S,S)-TsNCHPhCHPhNH] (M = Ir, Rh, Cp* = pentamethylcyclopentadienyl, Ts = p-toluenesulfonyl, Ph = C6H5) and Ru[κ2(N,N‘)-(S,S)-TsNCHPhCHPhNH](p-cymene), react with acidic alcohols, CF3CH2OH or phenols, to give the corresponding alkoxide complexes, which are readily convertible to metallacycles via intramolecular C−H bond activation of the aromatic group on the diamine ligand. For example, the Ir and Rh amide complexes are transformed to the metallacycles Cp*M[κ3(N,N‘,C)-(S,S)-CH3C6H3SO2NCHPhCHPhNH2] (M = Ir, Rh), while the Ru amide complex having structures isoelectronic with the Cp*Ir complex gives two types of metallacycles, Ru[κ3(N,N‘,C)-(S,S)-CH3C6H3SO2NCHPhCHPhNH2](p-cymene) and Ru[κ3(N,N‘,C)-(S,S)-TsNCHPhCH(C6H4)NH2](p-cymene), which are formed by the C−H bond activation of an aromatic ring in either the Ts group or the diamine ligand. NMR study for the cyclometalation of the Ir amide complex with phenols suggests that the reaction proceeds through the phenoxide complexes as intermediates.