“…Reduction of [Os 3 (CO) 10 ( μ -H)( μ -OSiPh 2 R ‘ )] (R ‘ = Ph, OH, OSiPh 2 OH) and [Os 3 (CO) 10 ( μ -H)( μ -OH)] . Recently some of us reported that both silica-anchored [Os 3 (CO) 10 (μ-H)(μ-OSi⋮)] and silica-supported [Os 3 (CO) 10 (μ-H)(μ-OH)] can be selectively reduced to various carbonyl clusters ([Os 3 (CO) 12 ], [H 4 Os 4 (CO) 12 ], [H 3 Os 4 (CO) 12 ] - , [H 2 Os 4 (CO) 12 ] 2- , [Os 5 C(CO) 14 ] 2- , and [Os 10 C(CO) 24 ] 2- ) by reductive carbonylation or hydrogenation, under appropriate conditions, in the presence of alkali-metal carbonates. , For a given set of reaction parameters (nature and quantity of alkali-metal carbonate, temperature, gas-phase composition), the selectivity starting from silica-anchored [Os 3 (CO) 10 (μ-H)(μ-OSi⋮)] and silica-supported [Os 3 (CO) 10 (μ-H)(μ-OH)] is similar to that observed starting from silica-supported [Os(CO) 3 Cl 2 ] 2 . , This evidence does not allow us to discriminate between silica-anchored [Os 3 (CO) 10 (μ-H)(μ-OSi⋮)] and silica-supported [Os 3 (CO) 10 (μ-H)(μ-OH)] as intermediates in the silica-mediated synthesis of different osmium carbonyl clusters starting from [Os(CO) 3 Cl 2 ] 2 . , In fact, these two potential intermediates may interconvert under reaction conditions; therefore, due to the presence of surface water, the surface species [Os 3 (CO) 10 (μ-H)(μ-OSi⋮)] could first hydrolyze to the more reactive molecular species [Os 3 (CO) 10 (μ-H)(μ-OH)], which could be the key intermediate also in the surface-mediated synthesis of [H 4 Os 4 (CO) 12 ] by easy hydrogenation of silica physisorbed [Os 3 (CO) 12 ]. , …”