The tetraruthenium cluster complex [Ru 4 (μ 4 -κ 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.