Reduction of diruthenium(II,III) carboxylate compounds with hydroquinone: a facile preparation of diruthenium(II) complexes

The synthesis of the diruthenium(II) compounds [Ru-2(mu-O2CR)(4)(MeOH)(2)] [R = Me (1), Ph (2), CMePh2 (3) C6H4-p-OMe (4), C6H4-p-CMe3 (5)] by reaction of [Ru-2(mu-O2CR)(4)]+BF4- with hydroquinone, under a nitrogen atmosphere, in the presence of a base is described. This reaction constitutes an easy via to the preparation of diruthenium(II) compounds. The structure of the complexes [Ru-2(mu-O-2-CMe)(4)(MeOH)(2)] (1) and [Ru-2(mu-O2CPh)(4)(thf)(2)] (2b) is established by single crystal X-ray diffraction. These compounds show a diruthenium(II) unit bridged by four carboxylate ligands with the axial positions occupied by methanol and tetrahydrofuran molecules for 1 and 2b, respectively. Complex 1 shows, in the solid state, polymeric chains in which the molecules [Ru-2(mu-O2CMe)(4)-(MeOH)(2)] are linked by hydrogen bonds. (C) 2004 Elsevier B.V. All rights reserved.