Crystal structure of {(E)-2-[(3,4-dimethoxyphenylimino)methyl]phenolato-κ2 N,O 1}bis[2-(pyridin-2-yl)phenyl-κ2 C 1,N]iridium(III) dichloromethane disolvate

The two IrIII atoms in the title structure have distorted octahedral coordination spheres, being C,N-chelated by two main 2-phenylpyridine ligands and N,O-chelated by one ancillary 2-[(2,4-dimethoxyphenylimino)methyl]phenolato ligand.


Chemical context
Heteroleptic iridium(III) complexes bearing a coordinating phenylpyridine ligand are of great interest because of their potential applications in the field of organic light-emitting diodes (OLEDs), as phosphorescence sensors and in photocatalysis (Evans et al., 2006;Maity et al., 2015;Alam et al., 2017). In particular, cyclometalated Ir III complexes with imine-based ancillary ligands exhibit strong aggregationinduced phosphorescent emission (AIPE) in the solid state (Howarth et al., 2014;You et al., 2008). The photophysical properties of these complexes are governed mainly by the coordination environment around the metal ions and the ligand architecture. Hence a small change in the ligand moiety can alter the ground as well as excited states of the metal complexes, making it important to analyze in detail the coordination environment of iridium complexes to understand the origin of phosphorescence in the solid state (Pal & Singh, 2013;Goo et al., 2016).
Here we report the crystal structure of the title compound, [Ir(C 11 H 8 N) 2 (C 15 H 14 NO 3 )]Á2CH 2 Cl 2 , a heteroleptic Ir III complex containing a derivative of a salicylimine ligand. ISSN 2056-9890

Structural commentary
The asymmetric unit of the title complex consists of two iridium complexes together with four dichloromethane solvent molecules. One of the solvent molecules is disordered over two sets of sites. Each complex molecular unit ( Fig. 1) consists of one Ir III ion, two C,N-chelating 2-phenylpyridine ligands, and one N,O-chelating 2-((2,4-dimethoxyphenylimino)methyl)phenolate anion. Each Ir III ion adopts a distorted octahedral coordination environment defined by two phenyl C, two pyridine N, and one imine and one phenolic O atoms. Selected bond lengths and angles are given in Table 1 for both complex molecules.
In complex molecule 1 (Ir1), the equatorial plane is defined by atoms O1/N3/C11/C12, the mean deviation from the leastsquares plane being 0.044 Å . The Ir1 III ion is displaced by 0.0396 (17) Å from the equatorial plane towards the axial N1 atom. The two 2-phenylpyridine ligands are nearly planar, with dihedral angles between the aromatic rings of 1.42 (13) (between rings C6-C11 and N1-C5) and 0.60 (13) (between rings C12-C17 and N2-C22). View of the asymmetric unit of the title compound with the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. Purple and green dashed lines represent intra-and intermolecular C-HÁ Á Á interactions, respectively. Solvent molecules are omitted for clarity. perpendicular to each other, with a dihedral angle between the least-squares planes of 89.91 (11) . The coordinating C atoms (C11, C12) are trans to the phenolic O1 atom and the imine N3 atom of the anionic ligand, and the two pyridine N atoms (N1 and N2) are also trans to each other. In complex molecule 2 (Ir2), a similar bonding situation is observed, with the phenyl C atoms C38 and C49 trans to the O4 and N6 atoms of the 2-[(2,4-dimethoxyphenylimino)methyl]phenolate anion. The equatorial plane is formed by atoms O4/C49/C38/N6. The mean deviation from the leastsquares plane is 0.055 Å and the Ir2 III ion is displaced by 0.0237 (17) Å from the equatorial plane towards the axial N4 atom. The deviation from a perpendicular arrangement of the two 2-phenylpyridine ligands is slightly higher than in complex 1 [the dihedral angle between the least-squares planes is 85.13 (11) ], likewise the deviation from planarity with dihedral angles of 1.69 (13) (between rings C49-C54 and N5-C59) and 3.36 (13) (between rings C38-C43 and N4-C48), respectively.
The Ir-C, Ir-N, and Ir-O bond lengths, as shown in Table 1

Figure 2
Packing plot of the molecular components in the title compound. Cyan lines represent intermolecular short contact. Solvent molecules are omitted for clarity.
reported compound (Goo et al., 2016) where this packing feature is present.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 3. All H atoms were positioned geometrically and refined using a riding-model approximation: C-H = 0.95 Å for Csp 2 -H and 0.99 Å for methylene C-H with U iso (H) = 1.2U eq (C); C-H = 0.98 Å with U iso (H) = 1.5U eq (C) for methyl H atoms. One of the four dichloromethane solvent molecules shows disorder over two sets of sites [occupancy ratio 0.79 (2):0.21 (2)].

Funding information
This work was supported by Kumoh National Institute of Technology.