The crystal and molecular structure of chlorocarbonylnitrosylbis(triphenylphosphine)iridium tetrafluoroborate, [IrCl(CO)- (NO)(P(C6H5)3)2] [BF4], has been determined from three-dimensional X-ray data collected by counter methods. The material crystallizes in space group C2h 5-P21/c of the monoclinic system with four molecules in a cell of dimensions a = 19.417 (7), b = 9.965 (3), c = 20.886 (8) Å, β = 117.70 (2)°. The observed and calculated densities are 1.67 and 1.677 g cm−3, respectively. Least-squares refinement of the structure has led to a final value of the conventional R factor (on F) of 0.037 for the 2410 independent reflections having F2 > 3σ(F2). The nitrosyl group has been distinguished from the carbonyl group and has been shown to be bonded to the metal through the nitrogen, by examination of the root-mean-square amplitudes of vibration of the various atoms. The crystal structure consists of well-separated monomeric ions. The coordination geometry around the Ir is that of a tetragonal pyramid, with CO, Cl, and trans-P atoms in the basal plane and the N of the nitrosyl group at the apex; the Cl and CO lie slightly below the plane perpendicular to the Ir-N bond and passing through the Ir atom, the N-Ir-Cl and N-Ir-C angles being 101.3 (3) and 97.4 (5)°, respectively. The basal interatomic distances are normal, but the Ir-N bond length of 1.97 (1) Å is long. The nitrosyl group is bonded to the metal in an unusual way, the Ir-N-O angle being 124.1 (9)°. This is the first accurately documented example of a distinctly bent M-N-O linkage in a metal-nitrosyl complex. The basic geometry of the complex is similar to that of the analogous S02 complex, IrCl(CO)- (SO2)(P(C6H5)3)2, and markedly different from that of the O2 complex, IrCl(CO)(O2)(P(C6H5)3)2.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry