Crystal structure of {(E)-2-[(phenylimino)methyl]phenolato-κ2 N,O}bis[2-(pyridin-2-yl)phenyl-κ2 C 1,N]iridium(III) dichloromethane monosolvate

The IrIII atom in the title molecule adopts a distorted octahedral coordination sphere, being C,N-chelated by two 2-(pyridin-2-yl)phenyl ligands and N,O-chelated by one ancillary 2-[(phenylimino)methyl]phenolate ligand. The crystal packing is stabilized by intermolecular C—H⋯π interactions and π–π interactions.

In the title compound, [Ir(C 11 H 8 N) 2 (C 13 H 10 NO)]ÁCH 2 Cl 2 , the Ir III ion is sixcoordinated by two C,N-bidentate 2-(pyridin-2-yl)phenyl ligands and one N,Obidentate 2-[(phenylimino)methyl]phenolate anion, giving rise to a distorted octahedral environment. The C,N-bidentate ligands, in which the C and N atoms are statistically disordered over two sites and therefore both pairs of C and N atoms are trans and cis relative to each other, are almost perpendicular to each other [the dihedral angle between the least-square planes is 87.00 (4) ]. An intramolecular C-HÁ Á ÁO hydrogen bond, as well as intermolecular C-HÁ Á Á interactions andinteractions, contribute to the stabilization of the molecular and crystal structure.

Chemical context
Cyclometallated Ir III complexes are of great interest due to their excellent phosphorescent properties and electroluminescence applications. In particular, heteroleptic Ir III complexes with imine-based ancillary ligands exhibit aggregation-induced phosphorescent emission (AIPE), resulting in enhanced phosphorescence phenomena in the solid state (Howarth et al., 2014;You et al., 2008;Zhao et al., 2008). To uncover the origin of the intriguing AIPE, it is crucial to analyse the solid-state structures of relevant Ir III complexes besides undertaking spectroscopic and theoretical investigations. Here we report the crystal structure of the title compound, [Ir(C 11 H 8 N) 2 (C 13 H 10 NO)]ÁCH 2 Cl 2 , a heteroleptic Ir III complex with an ancillary salicylimine ligand.

Structural commentary
The molecular components of the title structure are shown in Fig. 1. The asymmetric unit consists of one Ir III ion, two 2-(pyridin-2-yl)phenyl ligands, and one 2-[(phenylimino)methyl]phenolate anion. The Ir III ion adopts a distorted octahedral coordination geometry, being N,O-chelated by the 2-[(phenylimino)methyl]phenolate ligand and C,N-chelated by two 2-(pyridin-2-yl)phenyl ligands, in which the C and N atoms are equally disordered over two sites and therefore both pairs of C and N atoms are trans and cis relative to each other. The equatorial plane is formed by N1/O1/N2/C12 atoms, the mean deviation from the least-squares plane being 0.002 Å . The Ir III ion is displaced by 0.0481 (9) Å from the equatorial plane towards the axial imino N3 atom. The C,Nbidentate ligands are nearly perpendicular to each other, with a dihedral angle between the least-squares planes of 87.00 (4) . Within the C,N-bidentate ligands, the dihedral angles between the aromatic rings are 3.70 (10) (between rings C1-C6 and N1/C7-C11) and 7.67 (16) (between rings C12-C17 and N2/C18-C22). As shown in Table 1, the Ir-C, Ir-N and Ir-O bond lengths of the title compound are within the ranges reported for similar Ir III compounds, e.g. {(E)-2-[(2,6diisopropylphenylimino)methyl]phenolato-2 N,O}bis(2-phenylpyridine-2 C,N)iridium(III) (Howarth et al., 2014) (You et al., 2008).

Supramolecular features
The molecular structure of the title compound is stabilized by an intramolecular C-HÁ Á ÁO hydrogen bond and intermolecular C-HÁ Á Á interactions between the dichloromethane solvent molecule and the phenyl rings of the C,Nbidentate ligand ( Fig. 1 and Table 2). Additionally, intermolecular C-HÁ Á Á interactions (Table 2) andinteractions [Cg1Á Á ÁCg1 ii = 3.6231 (12) Å and Cg3Á Á ÁCg4 View of the molecular structure of the title compound, showing the atomnumbering scheme. Displacement ellipsoids are drawn at the 50% probability level; red and sky-blue dashed lines represent intermolecular C-HÁ Á Á hydrogen bonds and intramolecularinteractions, respectively. H atoms have been omitted for clarity.

Figure 2
Packing plot of the molecular components in the title compound. Yellow and black dashed lines represent intermolecular C-HÁ Á Á andstacking interactions, respectively. H atoms not involved in intermolecular interactions and dichloromethane solvent molecules have been omitted for clarity. Table 2 Hydrogen-bond geometry (Å , ).

Synthesis and crystallization
The title compound was prepared according to a reported procedure (You et al., 2008). Single crystals suitable for X-ray diffraction were grown by slow diffusion of n-hexane into a CH 2 Cl 2 solution of the title compound at room temperature.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 3. The positions of the N atoms in the 2-(pyridin-2-yl)phenyl unit could not be discriminated from the difference in the displacement parameters, and free refinement of the N and C atoms revealed a lower and higher electron density, respectively, as expected for full occupancy and without disorder. Therefore, atoms N1 and C1A, C11 and N1A, N2 and C2A, and C22 and N2A were refined at the same sites with site occupancy factors of 0.5 using EXYZ/EADP constrains. All H atoms were positioned geometrically and refined using a riding model, with C-H = 0.  Computer programs: APEX2 and SAINT (Bruker, 2013), SHELXS97 and SHELXTL (Sheldrick, 2008), SHELXL2014 (Sheldrick, 2015) and DIAMOND (Brandenburg, 2010).

sup-1
Acta Cryst. program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015); molecular graphics: DIAMOND (Brandenburg, 2010); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).  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.