Crystal structure of fac-[2-(4-methyl-5-phenylpyridin-2-yl)phenyl-κ2 C 1,N]bis[2-(pyridin-2-yl)phenyl-κ2 C 1,N]iridium(III)

The IrIII atom in the title molecule adopts a distorted octahedral C3N3 coordination environment, being C,N-chelated by two 2-(pyridin-2-yl)phenyl ligands and one 2-(4-phenyl-5-methylpyridin-2-yl)phenyl ligand.


Chemical context
Cyclometallated iridium(III) complexes with the chelating ligand 2-phenylpyridine (C^N) are of great interest in phosphorescence organic light-emitting diodes (OLEDs) due to their high quantum efficiency and easy tuning emission energy (Kang et al., 2013). In general, iridium(III) complexes with chelating C^N ligands can be divided into two groups, homoleptic and heteroleptic complexes, according to the coordination environment of the central Ir III atom. The structural characteristics involving other chemical/electronic properties for both homoleptic Ir(C^N) 3 and heteroleptic Ir(C^N) 2 (L^X) complexes, where L^X is a monoanionic O^O or N^O ligand, have been well explored over the past two decades (Chi & Chou, 2010). However, reports of the molecular and crystal structures of heteroleptic Ir III compounds with the same chelating modes, viz. Ir(C^N) 2 (C^N) 0 , are very scarce compared to those for Ir(C^N) 2 (L^X) (Jung et al., 2012;Natori et al., 2013). Herein, we describe the structure of the title Ir III complex, fac-{2-[(4-phenyl-5-methyl)pyridine-2-yl]phenyl-2 C 1 ,N}bis[2-(pyridine-2-yl)phenyl-2 C 1 ,N]iridium(III), which was synthesized by the reaction of [(C^N) 2 Ir(-Cl)] 2 and 4-methyl-2,5-diphenylpyridine in the presence of Ag I .

Structural commentary
In the title compound, the asymmetric unit comprises of one Ir III ion, two 2-phenylpyridine ligands, and one 4-methyl-2,5diphenylpyridine ligand (Fig. 1). The Ir III ion is six-coordinated by the three C,N-bidentate ligands, giving rise to a distorted octahedral coordination environment with bond angles falling in the range 79.27 (12) to 97.37 (13) . As shown in Table 1, the Ir-C and Ir-N bond lengths in the title compound are within the ranges reported for similar Ir III compounds (Jung et al., 2012). The pyridyl N atoms of the three ligands are arranged in a fac-configuration around the octahedrally coordinated Ir III ion. The equatorial plane is defined by the N1/N3/C14/C11 atoms, the mean deviation from the least-squares plane being 0.081 Å . The Ir III ion lies almost in the equatorial plane with a deviation of 0.0069 (15) Å . Within the 2-(pyridine-2-yl)phenyl ligands, the dihedral angles between the aromatic rings are 5.6 (2) (between rings N1/C1-C5 and C6-C11) and 5.9 (2) (between rings N3/C30-C34 and C35-C40). Within the 2-[(4-phenyl-5methyl)pyridine-2-yl]phenyl ligand, the dihedral angles between the central pyridine ring and the phenyl rings at either end are 1.3 (2) and 43.84 (12) for the C13-C18 and C22-C27 rings, respectively.

Synthesis and crystallization
The ligand 4-methyl-2,5-diphenylpyridine was synthesized according to a literature procedure (Zhou et al., 2013). The title Ir III complex was also prepared according to a literature protocol (Jung et al., 2012). Crystals of the title complex were obtained by allowing a dichloromethane/hexane solution to evaporate slowly at room temperature.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 3

Figure 1
View of the molecular structure of the title compound, showing the atomnumbering scheme. Displacement ellipsoids are drawn at the 50% probability level. Table 2 Hydrogen-bond geometry (Å , ).

fac-[2-(4-Methyl-5-phenylpyridin-2-yl)phenyl-κ 2 C 1 ,N]bis[2-(pyridin-2-yl)phenyl-κ 2 C 1 ,N]iridium(III)
Crystal data Special details Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.