Bis[2-(1,3-benzothiazol-2-yl)phenyl-κ2 C 1,N][1,3-bis(4-bromophenyl)propane-1,3-dionato-κ2 O,O′]iridium(III)

The title complex, [Ir(C15H9Br2O2)(C13H8NS)2], lies about a crystallographic twofold rotation axis passing through the IrIII atom and the central C atom of the bis(bromophenyl)propane-1,3-dionate ligand. The IrIII atom adopts a distorted octahedral geometry coordinated by two N atoms in the axial positions, and two C and two O atoms in the equatorial plane. The dihedral angle between the two thiazole ring systems in the complex is 77.45 (10)°.

The title complex, [Ir(C 15 H 9 Br 2 O 2 )(C 13 H 8 NS) 2 ], lies about a crystallographic twofold rotation axis passing through the Ir III atom and the central C atom of the bis(bromophenyl)propane-1,3-dionate ligand. The Ir III atom adopts a distorted octahedral geometry coordinated by two N atoms in the axial positions, and two C and two O atoms in the equatorial plane. The dihedral angle between the two thiazole ring systems in the complex is 77.45 (10) .
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: IS5287).

Young-Inn Kim, Seong-Jae Yun and Sung Kwon Kang Comment
Electrophosphorescent materials based on iridium(III) have been developed in order to apply for organic light-emitting diodes (OLEDs) (Ulbricht et al., 2009) because iridium(III) complexes possess relatively short excited state lifetimes, high quantum efficiencies (Liu et al., 2008;Hwang et al., 2005;Tsuboyama et al., 2003) and remarkable color tuning from red to blue by a modification of the ligand structures (Bera et al., 2007). Recently, we reported red phosphorescent iridium complexes (Sengottuvelan, Yun, Kim et al., 2013;Sengottuvelan et al., 2011) for an application for OLEDs.
Herein, an orange-red emissive complex, a new heteroleptic cyclometalated iridium(III) complex containing two 2phenylbenzothiazole as main ligands and 1,3-bis(p-bromophenyl)-1,3-propanedione as an ancillary ligand, is prepared and its crystal structure is reported. The title complex emitted at 617 (595 s h.) nm in dichloromethane at room temperature.
In the title compound ( Fig. 1), the Ir III atom lies on a twofold axis and is coordinated by two C atoms, two N atoms, and two O atoms of three bidentate ligands in a distorted octahedral geometry. The angles around Ir atoms are in the range of 79.67 (14)-97.27 (14)°. The Ir-C bond distances of 1.996 (4) Å are shorter than the Ir-N distances of 2.060 (3) Å due to the stronger trans influence of the phenyl ring compared to the 5-membered thiazole ring (Table 1). The bidentate 1,3benzothiazol-2-ylphenyl ligand (N12-C26) is almost planar, with an r.m.s. deviation of 0.051 Å from the corresponding least-squares plane defined by the fifteen constituent atoms.
Synthesis of 1,3-bis(p-bromophenyl)-1,3-propanedione (dbacac): A mixture of a sodium hydride in oil dispersion (60%) and ethyl 4-bromobenzoate in 20 ml of dry THF was heated to 60 °C. 4-Bromoacetophenone in 8 ml in dry THF was added dropwise to the mixture. After the reaction temperature was held at 60 °C for 1 day, the mixture was poured into water and then neutralized with hydrochloric acid. The resulting precipitate was recrystallized from dichloromethane and hexane to give pale ivory powders.
Synthesis of title complex: The reaction of IrCl 3 3H 2 O with pbt in a 3:1 mixture of 2-ethoxyethanol and water at 135 °C gave cyclometallated iridium(III) µ-chloro-bridged dimer, [(pbt) 2 Ir(µ-Cl)] 2 . The prepared iridium(III) dimer complex, sodium carbonate and dbacac were dissolved in 2-ethoxyethanol. The mixture was heated at 125 °C for 8 h. The mixture was extracted with dichloromethane and dried over anhydrous magnesium sulfate. The crude product was flash chromatographed on silica gel using dichloromethane/methanol as an eluent. The red crystals were obtained from hexane/chloroform solution by slow evaporation at room temperature.

Refinement
All H atoms were positioned geometrically and refined using a riding model, with C-H = 0.93 Å and with U iso (H) = 1.2U eq (C). The maximum and minimum residual electron density peaks were located at 0.84 and 0.81 Å, respectively, from atom Ir1.

Figure 1
Molecular structure of the title compound, showing the atom-numbering scheme and 30% probability ellipsoids.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq  (5)