The crystal and molecular structure of iodocarbonylnitrosylbis(triphenylphosphine)iridium tetrafluoroborate-benzene, [IrI(CO)(NO)(P(C₆H₅)₃)₂][BF₄]·C₆H₆

The crystal and molecular structure of iodocarbonylnitrosylbis(triphenylphosphme)iridmm tetrafluoroborate-benzene, [IrI(CO)(NO)(P(C₆H₅)₃)₂][BF₄]·C₆H₆, has been determined from three-dimensional X-ray data collected by counter methods. The material crystallizes in space group D¹⁵_2h-Pbca of the orthorhombic system with eight molecules in a cell of dimensions a = 21.397 (7), b = 21.086 (7), and c = 18.524 (6) Å. The observed and calculated densities are 1.71 (1) and 1.704 g cm^-3, respectively. Leaśt-squares refinement of the structure has led to a final value of the conventional R factor (on F) of 0.059 for the 1162 independent reflections having F² > 2σ(F²). The crystal structure consists of well-separated monomeric units. The coordination geometry around the Ir is that of a distorted tetragonal pyramid, with CO, I, and trans-P atoms in the basal plane and the N of the nitrosyl group at the apex; the Ir lies slightly above the basal plane. The Ir-C bond length of 1.70 (5) Å is short, but the Ir-N bond length of 1.89 (3) Å is long. The Ir-N-O angle is 125 (3)°. The geometry of the cation is very similar to that of the chloro analog, IrCl(CO)(NO)(P(C₆H₆)₃)⁺₂, and lends support to the hypothesis that NO⁺ is acting as a σ acceptor in these systems.