Synthesis and molecular structure of the trinuclear ruthenium cluster cations [H3Ru3{C6H5(CH2)2OC(O)C6H5}(C6Me6)2(O)]+ and [H3Ru3{C6H5(CH2)2OC(O)(CH2)3C6H5}(C6Me6)2(O)]+

Benzoic acid 2-cyclohexa-1,4-dienyl ethyl ester (1), and 4-phenylbutyric acid 2-cyclohexa-1,4-dienyl ethyl ester (2) are prepared by reacting, respectively, benzoic acid and 4-phenylbutyric acid with 2-cyclohexa-1,4-dienyl ethanol. These dienyl ester derivatives react with RUCl3 . n H2O in refluxing ethanol to afford in good yield [Ru{C6H5(CH)(2)OC(O)C6H5}Cl-2](2) (3), and [Ru{C6H5(CH2)(2) OC(O)(CH2)(3)C6H5}Cl-2](2) (4). The trinuclear arene ruthenium cluster cations [H3Ru3{C6H5(CH2)(2)OC(O)C6H5)(C6Me6)(2)(O)](+) (5), and [H3Ru3{C6H5(CH2)(2)OC(O)(CH2)(3)C6H5}(C6Me6)(2)(O)](+) (6) are synthesised from the dinuclear precursor [H3Ru2C6Me6)(2)](+), and the mononuclear complexes [Ru{C6H5(CH2)(2)OC(O)C6H5}(H2O)(3)](2+) and [Ru{C6H5(CH2)(2)OC(O)(CH2)(3)C6H5}(H2O)(3)](2+), accessible, respectively, from 3 and 4 in aqueous solution. The water-soluble trinuclear cluster cations 5, and 6 possess a phenyl substituent attach to their side-arm which can act as a substrate for hydrogenation. The single-crystal X-ray structure analyses of [5][PF6], and [6][PF6] have been determined. (C) 2003 Elsevier B.V. All rights reserved.