Surface-mediated organometallic synthesis: high-yield syntheses of [Rh4(CO)12], [Rh6(CO)16], [Rh5(CO)15]− and [Rh12(CO)30]2− by controlled reduction of silica-supported RhCl3 or [Rh(CO)2Cl]2 in the presence of CH3CO2Na, Na2CO3 or K2CO3

The reductive carbonylation under 1 atm of CO of [Rh(CO)2Cl]2 supported on a silica surface added with a base such as CH3CO2Na, Na2CO3 or K2CO3, can be directed toward the formation of [Rh4(CO)12], [Rh6(CO)16] or K2[Rh12(CO)30] by controlling (i) the nature and amount of base; (ii) the amount of surface water; (iii) the reaction time; (iv) the temperature. Physisorbed [Rh6(CO)16] can also be prepared by direct controlled reductive carbonylation of RhCl3·nH2O supported on silica in the presence of well controlled amounts of CH3CO2Na. The neutral clusters [Rh4(CO)12] and [Rh6(CO)16] are easily recovered by extraction with dichloromethane whereas treatment of the generated silica-supported K2[Rh12(CO)30] with tetrahydrofuran affords K2[Rh12(CO)30] (by working under N2) or K[Rh5(CO)15] (by working under CO) in agreement with the easy conversion of these two clusters in solution. These efficient silica-mediated syntheses are comparable to conventional synthetic methods carried out in solution.