CRYSTAL AND MOLECULAR STRUCTURE OF DIIODOCARBOMETHOXYCARBONYL(2,2'-BIPYRIDYL)IRIDIUM [IRI2CO(C10H8N2)(C2H3O2)]

Diiodocarbomethoxycarbonyl(2,2'-bipyridyl)iridium [IrI2(COOCH3)(CO)(C10N2H8)] crystallizes in space group C2h5, P21/n, with unit cell dimensions a = 8.92 (1) Å, b = 17.87 (2) Å, c = 10.93 (1) Å, β = 103.55 (10)°, and Z = 4. The structure has been determined from about 1500 independent reflections (measured by counter methods) and refined by full-matrix least squares to a conventional R factor of 0.043. It consists of a packing of discrete monomeric molecules in which the metal atom displays a distorted octahedral coordination with the two iodine atoms in trans positions. On the basis of the observed Ir-C distance (2.05 (2) Å), the carbomethoxy group seems to be linked to the metal via a pure σ bond. The observed coplanarity of the -COO group with the metal atom, the carbonyl, and the two nitrogen atoms of bipyridine seems to be due to an angulated hydrogen bond connecting the “ketonic” oxygen of the carbomethoxy group with an α-carbon atom of the bipyridine. The Ir-C bond connecting the metal with the carbonyl ligand is rather short (1.80 (2) Å) although the C-O bond (1.11 (2) Å) and the stretching frequency (2050 cm-1) do not indicate a particularly strong metal-carbonyl interaction. Owing to a steric repulsion of two hydrogen atoms, the 2,2'-bipyridine ligand is not planar, and, consequently, the chelate ring is also not planar. © 1969, American Chemical Society. All rights reserved.