OCTAHEDRAL IRIDIUM CARBONYL CLUSTERS - SYNTHESIS, CHARACTERIZATION AND SOLID-STATE STRUCTURE OF THE NITROSYL CLUSTER [IR-6(CO)(11)(MU-CO)(3)NO]-

The nitrosylcarbonyl cluster [Ir-6(CO)(14)NO](-) has been prepared by one-electron oxidation of [Ir-6(CO)(15)](2-), followed by addition of NO at low temperature. The structure of the salt [NMe(3)(CH(2)Ph)][Ir- 6(CO)(11)(mu-CO)(3)NO] was solved by direct methods and difference Fou rier techniques and refined down to R = 0.036, for 3239 observed refle ctions having I> 3 sigma(I). The cluster of idealized C-s point group symmetry contains an octahedral metal framework of iridium atoms, an N O group linearly bound, which acts as a three-electron donor, 11 termi nal and three edge-bridging carbonyl ligands. The Ir-N separation of 1 .75(3) Angstrom is the shortest metal-to-ligand bond distance. Average distances are: Ir-Ir = 2.773 Angstrom, Ir-C = 1.86 Angstrom, C-term-O -term = 1.16 Angstrom, Ir-C-bridg = 2.02 Angstrom, C-bridg-O-bridg = 1 .19 Angstrom.