The reaction of Ru3(CO)9(mu-3-S)2 (4) with W(CO)6 under UV irradiation yielded the complex Ru3(CO)9(mu-3-S)(mu-4-S)[W(CO)5] (5) in 29% yield. Spectral data indicate that 5 has a structure similar to its osmium homologue in which a W(CO)5 group is attached to one of the triply-bridging sulphido ligands in the cluster. The reaction of 4 with W(CO)5 (PMe2Ph) under UV irradiation yielded two isomeric cluster complexes, WRu3 (CO)11(PMe2PH)(mu-4-S)2 (6) 16% and (7) 7%. Compounds 6 and 7 were characterized by single-crystal X-ray diffraction analyses. These complexes were found to contain approximately square-planar arrangements of the four metal atoms with quadruply-bridging sulphido ligands on each side of the cluster. Compound 6 contains a PMe2Ph ligand on the tungsten atom. In compound 7 the PMe2Ph ligand is coordinated to the ruthenium atom across the square from the tungsten atom. Crystal data for 6: WRu3S2O11C19H11, M = 977.44, orthorhombic, P2(1)2(1)2(1) (No. 19), a = 13.794(2), b = 16.61(2), c = 11.780(2) angstrom, V = 2700(1) angstrom-3, D(c) = 2.45 g cm-3, Z = 4, lambda(Mo-K-alpha) = 0.71069 angstrom (graphite monochromator), mu = 62.1 cm-1. Methods: MITHRIL, difference Fourier, full-matrix least-squares. Refinement of 1960 reflections [F2 greater-than-or-equal-to 3-sigma(F2)], gave R and R(W) values of 0.027 and 0.027, respectively. Crystal data for 7: WRu3S2O11C19H11, M = 977.44, monoclinic, P2(1)/n (No. 14), a = 15.841(2), b = 8.818(1), c = 19.236(3) angstrom, beta = 98.04(1)-degrees, V = 2660.5(6) angstrom-3, D(c) = 2.49 g cm-1, Z = 4, lambda(Mo-K-alpha) = 0.17069 angstrom (graphite monochromator), mu = 63.1 cm-1. Methods: MITHRIL, difference Fourier, full-matrix least-squares. Refinement of 2880 reflections [F2 greater-than-or-equal-to 3-sigma(F2)], gave R and R(w) values of 0.024 and 0.025, respectively.