Syntheses, structures and chemistry of the high-nuclearity ruthenium hydride cluster anions [Ru10H2(CO)(25)](2-) and [RU(11)H(CO)(27)](3-)

Thermolysis of [Ru-3(CO)(12)] in ethanol yielded the decanuclear hydridoruthenium cluster dianion [Ru10H2(CO)(25)](2-) 1. When a mixture of methanol and water is employed as thermolysis solvent the undecaruthenium hydridoruthenium trianion [Ru11H(CO)(27)](3-) 2 is also formed. Crystal structure analysis of 1 as its [N(PPh(3))(2)](+) salt and 2 as its [NEt(3)(CH(2)Ph)](+) salt showed their metal core structures to be related, 2 being a square-faced capped congener of 1. Cluster 2 was alternatively formed in near-quantitative yields when [Ru-3(CO)(12)] was thermolysed in acetonitrile containing traces of water for several days. It was not possible to locate the hydride ligands in the structures by potential-energy-minimisation calculations, but strong signals were seen in the H-1 NMR spectra at delta -14.2 (s, 2 H) for 1 and at -5.47 (s, 1 H) for 2. On treatment of 1 and 2 with [Au(PPh(3))Cl] in the presence of TlPF6, 1 showed no reactivity, but 2 reacted smoothly adding one [Au(PPh(3))](+) moiety and giving a product characterised as [Ru11H(CO)(27){Au(PPh(3))}](2-) 3. The structural relationships between the known high-nuclearity ruthenium hydride carbonyl clusters are discussed, and their implications for a possible cluster build-up sequence considered.