(Pyridine-2-aldoximato-κ2 N,N′)bis[2-(pyridin-2-yl)phenyl-κ2 C 1,N]iridium(III)

In the title complex, [Ir(C11H8N)2(C6H5N2O)], the octahedrally coordinated IrIII atom is bonded to two 2-(pyridin-2-yl)phenyl ligands, through two phenyl C and two pydidine N atoms, and to one pyridine-2-aldoxime ligand through a pyridine N and an oxime N atom. The oxime O atom of the aldoxime unit forms intermolecular C—H⋯O hydrogen bonds, which result in a two-dimensional hydrogen-bonded polymeric network parallel to (100). C—H⋯π interactions are also observed.

In the title complex, [Ir(C 11 H 8 N) 2 (C 6 H 5 N 2 O)], the octahedrally coordinated Ir III atom is bonded to two 2-(pyridin-2-yl)phenyl ligands, through two phenyl C and two pydidine N atoms, and to one pyridine-2-aldoxime ligand through a pyridine N and an oxime N atom. The oxime O atom of the aldoxime unit forms intermolecular C-HÁ Á ÁO hydrogen bonds, which result in a two-dimensional hydrogen-bonded polymeric network parallel to (100). C-HÁ Á Á interactions are also observed.

Satyanarayan Pal and Bimal Chandra Singh Comment
Herein we describe the crystal structure of a neutral Ir(III) octahedral complex, namely [Ir(ppy) 2 (pyald)] (ppy = 2-phenylpyridine, pyald=2-pyridinealdoxime). The asymmetric unit is shown in Figure 2, which depicts that the Ir centre is coordinated by two 2-phenyl pyridine and one 2-pyridinealdoxime ligands. Two pyridine-N atoms from ppy moieties occupy the axial positions, whereas two phenyl-C from ppy ligands and two N atoms from the 2-pyridinealdoxime unit form the square plane. All three ligand tether the metal through five membered chelate rings, which ultimately lead to a Thus the negative charge is distributed over the pyridinealdoxime moiety through O1, N4, C28 and the pyridine ring.
The packing scheme is ruled by C-H···O hydrogen bonds (see, Desiraju,1991), which ultimately lead to the formation of a two dimensional hydrogen bonded polymeric structure ( Figure 3) and weaker intermolecular C-H···π interactions (see, Ma et al., 1997). These interactions are presented in Table 1.

Experimental
The iridium starting material [(ppy) 2 Ir(µ -Cl) 2 Ir(ppy) 2, ppy = 2-phenylpyridine] was prepared by following the procedure reported in the literature (see, Nonoyama,1974). The synthetic scheme of the title complex is shown in Figure 1. The detailed synthetic procedure is as follows: In a 100 ml round bottom flask, 2-pyridinealdoxime (266 mg, 2.18 mmol) was taken in 25 ml of 2-methoxy ethanol and added with triehtyl amine (220.6 mg, 2.18 mmol). The mixture was thoroughly mixed by stirring and added with [(ppy) 2 Ir(µ -Cl) 2 Ir(ppy) 2 ] (585 mg, 0.545 mmol) starting material. The resulted mixture was refluxed under a N 2 atmosphere for 18 hrs. The yellow precipitate thus formed was filtered and dried under vacuum. The complex was purified on a neutral aluminium oxide column by eluting with dichloromethane. The first yellow band was discarded as starting material and the second yellow band was collected as the title compound. The solution was evaporated and the supplementary materials remaining solid washed with hexane and dried under vacuum to yield an yellow powder (140 mg, 41%).

Special details
Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'s involving l.s. planes. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > 2σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq