Surface organometallic chemistry: the easy conversion of [Ir6(CO)16] supported on silica into [Ir4(CO)12]

[Ir6(CO)16] is deposited on silica from a solution as large crystallites. By heating under Ar at 100°C, a disaggregation of the crystallites occurs followed by conversion of the original [Ir6(CO)16] cluster to [Ir4(CO)12] and metal particles covered by CO. Treatment of these metal particles first with O2 and then with CO at 100°C affords [Ir4(CO)12], thus allowing a high conversion of [Ir6(CO)16] into [Ir4(CO)12]. More directly, [Ir6(CO)16] on silica may be converted to [Ir4(CO)12] by successive treatments under O2 and CO at 100°C. The formation of [Ir4(CO)12] from [Ir6(CO)16] supported on silica is inhibited by CO.