Synthesis of a trinuclear cation [H3Ru3(Fc-arene) (C6Me6)2(O)]+ containing a ferrocenyl group tethered to an arene ligand

Article abstract of DOI:10.1016/S0020-1693(03)00273-1

Ferrocene carboxylic acid 2-cyclohexa-1,4-dienyl-ethyl ester (1) is prepared from ferrocene carboxylic acid and 2-cyclohexa-1,4-dienyl-ethanol. This diene reacts with RuCl₃·nH₂O in refluxing ethanol to afford quantitatively [Ru(Fc-arene)Cl₂]₂ (2) (Fc-arene=ferrocene carboxylic acid phenethyl ester). The dinuclear complex 2 reacts with triphenylphosphine to give the mononuclear complex [Ru(Fc-arene)(PPh₃)Cl₂] (3). The trinuclear arene-ruthenium cluster cation [H₃Ru₃(Fc-arene)(C ₆Me₆)₂(O)]⁺ (4) is synthesised from the dinuclear precursor [H₃Ru₂(C₆Me ₆)₂]⁺ and the mononuclear complex [Ru(Fc-arene)(H₂O)₃]²⁺, accessible from 2 in aqueous solution. The water-soluble trinuclear cluster cation 4 catalyses the hydrogenation of benzene to give cyclohexane under biphasic conditions.