CARBIDE FORMING AND CLUSTER BUILDUP REACTIONS IN RUTHENIUM CARBONYL CLUSTER CHEMISTRY

The reinvestigation of an early synthesis of hexaruthenium carbido clusters has lead to the isolation of a number of new clusters which have been fully characterised by spectroscopic and crystallographic techniques. The thermolysis of Ru3(CO)12 in the presence of mesitylene (1,3,5-trimethylbenzene) at moderate temperatures yields two new clusters, [Ru6(μ4-η2-CO)2(CO)13(η6-C6H3Me3)] (I) and [HRu6(μ4-η2-CO)(CO)13(μ2-η7-C6H3Me2CH2)] (II), the structures and reactivity of which indicate the origin and mechanism of formation of the carbido-carbon in the hexaruthenium carbido clusters [Ru6C(CO)14(η6-C6H3Me3)] (III) and [Ru6C(CO)17] (IV). A further product of the reaction is the decaruthenium carbido cluster dianion [Ru10C(CO)24]2- (V) which has the tetracapped octahedral geometry. The monohydrido-cluster anion [HRu10C(CO)24]- (VI) may be synthesised quantitatively from V by protonation. The nature of the hydrido-ligand in VI has been investigated in the solid state by NMR spectroscopy and it has been found to be fluxional, its location being temperature dependent. The decanuclear dianion V has been found to react with mercury salts to yield the 21 metal atom cluster dianion [Ru18Hg3C2(CO)42]2- (VII) which consists of two tricapped octahedral nonaruthenium "subclusters" fused by a bi-facecapping (Hg3)2+ unit. © 1990.