Reactivity of the unsaturated triosmium cluster [(mu-H)Os-3(CO)(8){Ph2PCH2P(Ph)C6H4}] with dithiols; X-ray structures of [Os-3(CO)(8)(mu-SCH2CH2CH2S)(Ph2PCH2PPh2)]center dot 1/2CH(2)Cl(2) and [(mu-H)Os-3(CO)(7)(mu(3)-eta(3)-SCH2CH2CHS)(Ph2PCH2PPh2)]center dot 1/2H(2)O

Treatment of the unsaturated cluster [(mu -H)Os-3(CO)(8){Ph2PCH2P(Ph)C6H4}] (1) with HS(CH2)(n)SH (n = 1, 1,2-ethanedithiol; n = 2, 1,3-propanedithiol ) lead to the novel compounds [(mu -H)Os-3(CO)(8){mu -S(CH2)(n)S} {Ph2PCH2P (Ph)C6H4}] (9, n = 2, 49%; 12, n = 3, 56%) and [Os-3(CO)(3){mu -S(CH2)(n)S) (mu -Ph2PCH2PPh2)] (10, n = 2, 20%; 13, n = 3, 22%). The 52-electron compo unds 9 and 12 contain a bridging hydride, a bridging dithiolato and an orth ometallated 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 thermol ysis at 110 degreesC. Photolysis of 9 and 12 also gives 10 and 13 but in so mewhat lower yields. Compounds 10 and 13 undergo decarbonylation and alipha tic C-H bond activation of the dithiolato moiety at 128 degreesC to give [( mu -H)Os-3(CO)(7)(mu (3)-eta (3)-SCH2CHS)(Ph2PCH2PPh2] (11) and [(mu -H)Os- 3(CO)(7)(mu (3)-eta (3)-SCH2CH2CHS)(Ph2PCH2PPh2] (14) containing a bridging hydride, a triply bridging dithiolato and a bridging dppm ligand. Thermoly sis of 9 and 12 at 128 degreesC also gives 11 and 14 in 43 and 51% yields, respectively. Compounds 13 and 14 have been characterised by X-ray crystall ography. (C) 2001 Elsevier Science B.V. All rights reserved.