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 I atm of CO of [Rh(CO)(2)Cl](2) supported on a silica surface added with a base such as CH3CO2Na, Na2CO3 or K2CO3, can be directed toward the formation of [Rh-4(CO)(12)], [Rh-6(CO)(16)] or K-2[Rh-12(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 [Rh-6(CO)(16)] can also be prepared by direct controlled reductive carbonylation of RhCl3 . nH(2)O supported on silica in the presence of well controlled amounts of CH3CO2Na. The neutral clusters [Rh-4(CO)(12)] and [Rh-6(CO)(16)] are easily recovered by extraction with dichloromethane whereas treatment of the generated silica-supported K-2[Rh-12(CO)(30)] with tetrahydrofuran affords K-2[Rh-12(CO)(30)] (by working under N-2) or K[Rh-5(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. (C) 2003 Elsevier Science B.V. All rights reserved.