Surface-mediated organometallic synthesis: The activating role of silica for a high-yield route to [H4Os4(CO)(12)] and [HOs3(CO)(10)Y] (Y = OH, OR, Cl, Br, I, O2CR, SCN) clusters from [Os-3(CO)(12)]

Activation of [Os-3(CO)(12)] by the silica surface via reaction with surface silanol groups provides a new convenient general approach to the selective, high-yield synthesis of various osmium carbonyl clusters such as [H4Os4(CO)(12)] and [HOs3(CO)(10)Y] (Y = a three-electron donor such as OH, OR, Cl, Br, I, O2CR, and SCN). These silica-mediated syntheses compare favorably with the more conventional syntheses in solution because (i) differently from other related intermediates used in solution, silica-anchored [HOs3(CO)(10)(OSi=)] is easily obtained in quantitative yield starting from [Os-3(CO)(12)] in one step and (ii) the conversion of [HOs3-(CO)(10)(OSi=)] occurs in one pot usually in high yields and under mild reaction conditions. In addition, the related species [HOs3(CO)(10)(OH)], which can be obtained almost quantitatively by hydrolysis of [HOs3(CO)(10)(OSi=)], is even more reactive than its precursor and allows a three-step synthesis of various osmium clusters characterized by excellent total yields from [Os-3(CO)(12)].