Synthesis and characterization of organometallic ionic liquids and a heterometallic carbene complex containing the chromium tricarbonyl fragment

Direct reaction between [Cr(CO)6] and arenes with ionic substituents affords the corresponding arene-chromium tricarbonyl complexes, [Cr(CO)3(arene)], in only modest yield. In contrast, these complexes can be prepared in pure form in excellent yield from the reaction of [Cr(CO)3(η6-C6H5CH2Br)] with, for example, N-methylimidazole. The structures of [Cr(CO)3(η6-C6H5CH2MIM)]Br (MIM = 3-methylimidazolium), [Cr(CO)3(η6-C6H5CH2MMIM)]Br (MMIM = 2,3-dimethylimidazolium), and [Cr(CO)3(η6-C6H5CH2NMe2(CH3)2OH)]Br have been established by X-ray diffraction analysis. Subsequent exchange of the bromide anion for Tf2N- affords new organometallic salts with melting points below 70 degrees C. Reaction of the bromide salts include tosylation of [Cr(CO)3(η6-C6H5CH2NMe2(CH3)2OH)]Br to afford [Cr(CO)3(η6-C6H5CH2NMe2(CH2)2OTs)]Br and the formation of the heterometallic carbene complex [Ru(η6-p-cymene)Cl2{C4H5N2CH2Ph-η6-Cr(CO)3}]. Both compounds were characterized in the solid state by X-ray diffraction.