Abstract: Treatment of [Ru3(CO)10(μ-dppm)] (1) with PPh3 ent temperature in THF gave the known compound [Ru3(CO)7(μ3-CO)(μ3-S)(μ-dppm)] (2) and the new compound [Ru3(CO)6(μ3-CO)(μ3-S)(PPh3)(μ-dppm)] (3). Compound 3 can also be prepared by the room temperature reaction of 2 with PPh3 in the presence of Me3NO. A similar reaction of [Ru3(CO)7(μ3-S)2(μ-dppm)] (4) with PPh3 afforded (3), [Ru3(CO)6(μ3-S)2(PPh3)(μ-dppm)] (5) together with the previously reported compound [(μ-H)2Ru3(CO)7(μ3-S)(μ-dppm)] (6). In contrast, a similar treatment of the sulfur-selenium compound [Ru3(CO)7(μ3-S)(μ3-Se)(μ-dppm)](7) with PPh3 afforded only [Ru3(CO)6(μ3-S)(μ3-Se)(PPh3)(μ-dppm)] (8). Both compounds 5 and 8 exist as two isomers in solution, arising from the reversible migration of a metal–metal bond, induced by the dppm ligand. The reaction of 6 with PPh3 under the same conditions gave [(μ-H)2Ru3(CO)6(μ3-S)(PPh3)(μ-dppm)] (9). Protonation of 4 and 7 by trifluoroacetic acid gave the mono-protonated species [(μ-H)Ru3(CO)7(μ3-S)2(μ-dppm)]+ (10) and [(μ-H)Ru3(CO)7(μ3-Se)(μ3-S)(μ-dppm)]+ (11), respectively, isolated as their PF6 salts. All the compounds have been characterized by spectroscopic data together with single crystal X-ray diffraction studies for 3 and 5. [Copyright &y& Elsevier]