Reactivity of 1.4-benzoquinone with trinuclear ruthenium and osmium clusters: Facile hydrogenation of the quinoid fragment

Abstract

The reaction of [H2Os3(CO)10] with 1,4-benzoquinone yields initially a complex where the quinone bonds to the metal framework, both through a carbon atom of the ring and through an oxygen atom. Evidence suggests that this complex is a kinetic product which then transforms into complexes in which the quinone bonds through the oxygen atom. In one case, an oxygen atom of a hydroquinone moiety, bridges one of the metal–metal bonds, and in the other, a benzoquinone group acts, coordinated through the oxygen atoms, as a bridge between two trinuclear fragments. Similar products are obtained from the reaction of [Ru3(CO)12] with the same quinone in a hydrogen atmosphere although the presence of hydrogen leads to a partial hydrogenation of the benzoquinone ring. The reaction of [Os3(CO)10(MeCN)2] with the same quinone, formed a compound where the quinone is coordinate η2 through one of the double bonds of the ring to one of the osmium atoms. The products were characterized spectroscopically and; for four of the compounds; by X-ray crystallography.