Synthesis and characterization of a tetraruthenium butterfly cluster containing a quadruply-bridging ligand derived from an N,N'-dipyrid-2-ylurea

The tetraruthenium cluster complex [Ru-4(mu(4)-kappa(4)-dmpu)(CO)(10)], H(2)dmpu = N,N'-bis(6-methylpyrid-2-yl)urea, has been prepared by treating [Ru-3(CO)(12)] with H(2)dmpu in toluene at reflux temperature. An X-ray diffraction study has determined that this cluster has a butterfly metallic skeleton hold up by a doubly-deprotonated N,N'-bis(6-methylpyrid-2-yl)urea ligand (dmpu). This ligand has the pyridine N atoms attached to the wing-tip Ru atoms and the amido N atoms spanning Ru-Ru wing-edges, in such a way that the cluster has C-2 symmetry. The donor atoms of doubly-deprotonated N,N'-dipyrid-2-ylureas seem to be appropriately arranged to hold butterfly tetranuclear clusters. (c) 2007 Elsevier B.V. All rights reserved.