Reactivity of the unsaturated triosmium cluster [(μ-H)Os3(CO)8{Ph2PCH2P(Ph)C6H4}] with dithiols; X-ray structures of [Os3(CO)8(μ-SCH2CH2CH2S)(Ph2PCH2PPh2)]·1/2CH2Cl2 and [(μ-H)Os3(CO)7(μ3-η3-SCH2CH2CHS)(Ph2PCH2PPh2)]·1/2H2O

Treatment of the unsaturated cluster [(μ-H)Os3(CO)8{Ph2PCH2P(Ph)C6H4}] (1) with HS(CH2)nSH (n=1, 1,2-ethanedithiol; n=2, 1,3-propanedithiol) lead to the novel compounds [(μ-H)Os3(CO)8{μ-S(CH2)nS}{Ph2PCH2P(Ph)C6H4}] (9, n=2, 49%; 12, n=3, 56%) and [Os3(CO)8{μ-S(CH2)nS} (μ-Ph2PCH2PPh2)] (10, n=2, 20%; 13, n=3, 22%). The 52-electron compounds 9 and 12 contain a bridging hydride, a bridging dithiolato and an orthometallated dppm ligand while the 50-electron compounds 10 and 13 contain a doubly bridging dithiolato and a bridging dppm ligand. Compounds 9 and 12 are converted into 10 and 13 in 55 and 56% yields, respectively, by thermolysis at 110°C. Photolysis of 9 and 12 also gives 10 and 13 but in somewhat lower yields. Compounds 10 and 13 undergo decarbonylation and aliphatic C–H bond activation of the dithiolato moiety at 128°C to give [(μ-H)Os3(CO)7(μ3-η3-SCH2CHS)(Ph2PCH2PPh2] (11) and [(μ-H)Os3(CO)7(μ3-η3-SCH2CH2CHS)(Ph2PCH2PPh2] (14) containing a bridging hydride, a triply bridging dithiolato and a bridging dppm ligand. Thermolysis of 9 and 12 at 128°C also gives 11 and 14 in 43 and 51% yields, respectively. Compounds 13 and 14 have been characterised by X-ray crystallography.