Octahedral iridium carbonyl clusters. Synthesis, characterization and solid state structure of the nitrosyl cluster [Ir6(CO)11(μ-CO)3NO]-

The nitrosylcarbonyl cluster [Ir6(CO)14NO]- has been prepared by one-electron oxidation of [Ir6(CO)15]2-, followed by addition of NO at low temperature. The structure of the salt [NMe3(CH2Ph)][Ir6(CO)11(μ-CO)3NO] was solved by direct methods and difference Fourier techniques and refined down to R = 0.036, for 3239 observed reflections having I > 3σ(I). The cluster of idealized Cs point group symmetry contains an octahedral metal framework of iridium atoms, an NO group linearly bound, which acts as a three-electron donor, 11 terminal and three edge-bridging carbonyl ligands. The IrN separation of 1.75(3) Å is the shortest metal-to-ligand bond distance. Average distances are: IrIr = 2.773 A ̊, IrCterm = 1.86 A ̊, Cterm -Oterm = 1.16 A ̊, IrCbridg = 2.02 A ̊, Cbridg-Obridg = 1.19 A ̊. © 1995.