Chiral arene ruthenium complexes: synthesis and molecular structure of the enantiopure cluster cation (S)-[H3Ru3{C6H5[CH(CH3)CH2OH]}(C6Me6)2(O)]+

The reaction of enantiopure (R)-(2-cyclohexa-1,4-dienyl)propan-1-ol with ruthenium chloride hydrate yields, without racemization of the chiral ligand, the chloro-bridged dinuclear complex (S,S)-[RuCl2{C6H5[CH(CH3)CH2OH]}]2 (1). The dimer 1 reacts with triphenylphosphine to give the mononuclear complex (S)-[RuCl2{C6H5[CH(CH3)CH2OH]}(PPh3)] (2). A single-crystal X-ray structure anal. of 2 reveals the abs. configuration of the asym. carbon atom to have remained, the change from (R) to (S) being due to the priority change caused by coordination; in the solid state, one-dimensional hydrogen-bonded chains are formed between the hydroxy functions and chloro ligands of neighboring mols. The mononuclear cationic complex (S)-[Ru{C6H5[CH(CH3)CH2OH]}(H2O) 3]2+, formed in situ from 1 in aq. soln., reacts with the dinuclear complex [H3Ru2(C6Me6)2]+ to give a chiral trinuclear arene-ruthenium cluster, the cation (S)-[H3Ru3{C6H5[CH(CH3)CH2OH]}(C6Me6)2(O)]+ (3). This enantiopure cation has been isolated and characterized as its tetrafluoroborate salt. The single-crystal X-ray structure anal. of (S)-[3][BF4] shows a strong intramol. hydrogen bond between the ?3-oxo cap and the hydroxy function, which also persists in acetone solvent, as demonstrated by NMR spectroscopy. [on SciFinder(R)]