Faculté des sciences

endo and exo Coordination of Indanol: Synthesis, Isolation and Structural Characterisation of [H3Ru3 (endo-Indanol)(C6Me6)2(O)]+ and [H3Ru3 (exo-Indanol)(C6Me6)2 (O)]+ as Their Tetrafluoroborate Salts

Vieille-Petit, Ludovic ; Karmazin-Brelot, Lydia ; Labat, Gael ; Süss-Fink, Georg

In: European Journal of Inorganic Chemistry, 2004, vol. 19, p. 3907 - 3912

The reaction of 2,3,4,7-tetrahydro-1H-inden-2-ol with ruthenium chloride hydrate in refluxing ethanol yields the chloro-bridged dinuclear complex [RuCl2(indanol)]2 (1). The mononuclear complex [Ru(indanol)(H2O)3]2+ (2), formed in situ from 1 in aqueous solution, reacts with the dinuclear complex... More

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    Summary
    The reaction of 2,3,4,7-tetrahydro-1H-inden-2-ol with ruthenium chloride hydrate in refluxing ethanol yields the chloro-bridged dinuclear complex [RuCl2(indanol)]2 (1). The mononuclear complex [Ru(indanol)(H2O)3]2+ (2), formed in situ from 1 in aqueous solution, reacts with the dinuclear complex [H3Ru2(C6Me6)2]+ to give a trinuclear arene-ruthenium cluster as a mixture of two isomers, the cations [H3Ru3(endo-indanol)(C6Me6)2(O)]+ (3a) and [H3Ru3(exo-indanol)(C6Me6)2(O)]+ (3b), in a 1:1 ratio. The hydroxy function of the indanol ligand is oriented towards the μ3-oxo cap of 3a, whereas the OH group is bent away from the metal skeleton of 3b. These two isomers, which can easily be separated by silica-gel chromatography, were isolated and characterised as their tetrafluoroborate salts. The single-crystal X-ray structure analysis of [3a][BF4] shows a strong intramolecular hydrogen bond between the μ3-oxo ligand and the hydroxyl function, which even persists in acetone solution, as demonstrated by NMR spectroscopy. On the other hand, the hydroxy function of 3b was found to be free in the solid state as well as in solution, as shown by an X-ray crystal structure analysis and by NMR spectroscopy. The catalytic activities of the water-soluble trinuclear cations 3a and 3b for the hydrogenation of benzene to give cyclohexane under biphasic conditions are considerably different, the exo isomer 3b being more active than the endo isomer 3a.