Résultat de la recherche
Synthesis of a trinuclear cation [H3Ru3(Fc-arene)(C6Me6)2(O)]+ containing a ferrocenyl group tethered to an arene ligand
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)(C6Me6)2(O)]+ (4) is synthesised from the dinuclear precursor [H3Ru2 (C6Me6)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.
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 racemisation of the chiral ligand, the chloro-bridged dinuclear complex (S,S)-[RuCl2{C6H5[CH(CH3)CH2OH]}]2 (1). The dimer 1 reacts with triphenylphosphane to give the mononuclear complex (S)-[RuCl2{C6H5[CH(CH3)CH2OH]}(PPh3)] (2). A single-crystal X-ray structure analysis of 2 reveals the absolute configuration of the asymmetric carbon atom to have remained, the change from (R) to (S) being due to the priority change caused by coordination; in the solid state, onedimensional hydrogen-bonded chains are formed between the hydroxy functions and chloro ligands of neighbouring molecules. The mononuclear cationic complex (S)-[Ru{C6H5[CH(CH3)CH2OH]}(H2O)3]2+, formed in situ from 1 in aqueous solution, 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 characterised as its tetrafluoroborate salt. The single-crystal X-ray structure analysis of (S)-[3][BF4] shows a strong intramolecular hydrogen bond between the μ3-oxo cap and the hydroxy function, which also persists in acetone solvent, as demonstrated by NMR spectroscopy.