Catalytic hydrogenation of aromatics under biphasic conditions: isolation and structural characterisation of the cluster intermediate [(eta(6)-C6Me6)(2)(eta(6)-C6H6)Ru-3(mu(2)-H)(2)(mu(2)-OH)(mu(3)-O)](+)

The water-soluble cluster cation [(eta (6)-C6Me6)(2)(eta (6)-C6H6)Ru-3(mu ( 2)-H)(3)(mu (3)-O)](+) (2) catalyses the hydrogenation of benzene and benze ne derivatives to give the corresponding cyclohexanes under biphasic condit ions. The catalytic activity of 2 depends markedly on the substrate, an ext remely high activity being observed for ethylbenzene. The cationic species present in the catalytic mixture of the ethylbenzene hydrogenation could be isolated as the tetrafluoroborate salt and characterised as the cation [(e ta (6)-C6Me6)(2)(eta (6)-C6H6)Ru-3(mu (2)-H)(2)(mu (2)-OH)(mu (3)-O)](+) (3 ). With 3 as the catalyst, the catalytic activity is also much higher for o ther benzene derivatives. (C) 2001 Elsevier Science B.V. All rights reserve d.