Crystal and molecular structures of potassium pentachloro- and pentabromo-nitrosyliridate hydrate

Abstract

The crystal and molecular structures of the title compounds [Cl (I), Br (II)] have been investigated by use of diffractometer data. The compounds are isomorphous and isostructural, orthorhombic, space group Pnma or Pn2₁a, Z= 4; (I), a= 22.416(5), b= 6.935(1), c= 6.069(1)Å; (II), a= 23.272(9), b= 7.261(5), c= 6.302(3)Å. The structures were solved by the heavy-atom method and refined by full-matrix methods to R 0.049 [(I), 1 704 reflections] and 0.096 [(II). 1 291 reflections]. The iridium atom is octahedrally co-ordinated by five halide ions and the nitrogen atom of the NO ligand. Both structures show the trans-shortening influence of NO when co-ordinated formally as NO⁺. For (I) Ir–Cl(eq) distances are 2.335(2) and 2.342(2), and Ir–Cl(ax) 2.286(3)Å; for (II) the analogous distances are 2.475(3) and 2.485(3), and 2.419(4)Å. Ir–N and N–O distances and Ir–N–O angles are for (I) 1.76(1) and 1.12(2)Å, and 174.3(1)°, and for (II) 1.71(2) and 1.17(4)Å, and 170.3(3)°.