Bromidotricarbonyl[2-phenyl-5-(pyridin-2-yl-κN)-1,3,4-oxadiazole-κN 4]rhenium(I) dichloromethane monosolvate

In the title rhenium(I) complex, [ReBr(C13H9N3O)(CO)3]·CH2Cl2, the dichloromethane solvent molecule is disordered over two positions with an occupancy ratio of 0.81 (15):0.19 (15). The ReI atom is coordinated by two N atoms from a 2-phenyl-5-(pyridin-2-yl-κN)-1,3,4-oxadiazole (L) ligand, three C atoms from three carbonyl groups and a Br atom in a distorted octahedral geometry. The three rings in L are almost coplanar (a mean plane fitted through all non-H atoms of this ligand has an r.m.s. deviation of 0.063 Å), and the carbonyl ligands are coordinated in a fac arrangement.

In the title rhenium(I) complex, [ReBr(C 13 H 9 N 3 O)(CO) 3 ]Á-CH 2 Cl 2 , the dichloromethane solvent molecule is disordered over two positions with an occupancy ratio of 0.81 (15):0.19 (15). The Re I atom is coordinated by two N atoms from a 2-phenyl-5-(pyridin-2-yl-N)-1,3,4-oxadiazole (L) ligand, three C atoms from three carbonyl groups and a Br atom in a distorted octahedral geometry. The three rings in L are almost coplanar (a mean plane fitted through all non-H atoms of this ligand has an r.m.s. deviation of 0.063 Å ), and the carbonyl ligands are coordinated in a fac arrangement.

Comment
Interest in next generation displays and lighting technologies has stimulated research on organic light-emitting materials (Li et al., 2005;Wong et al., 2005), especially phosphorescent materials (Kim et al., 2006;Lee et al., 2005). As a result, transition metal phosphorescent complexes (Bernhard et al., 2002) have been studied intensively throughout the world. In order to further explore novel phosphorescent materials, several researchers paid attention to Re I complexes (Gong et al., 1998;Li et al., 2001), of which the d 6 electronic configuration is identical to that of the corresponding Os(II) and Ir(III) systems. Therefore, it is pressing to explore new Re I complexes served as luminescent materials. In this article, we report the successful synthesis of a novel Re I complex which contains the oxadiazole ligand of 2-phenyl-5-(pyridin-2-yl)-1,3,4-oxadiazole, and characterized its structure by single-crystal X-ray diffraction analysis. Its luminescent property will be further studied in the coming research.
The structure of complex [Re(CO) 3 (L)Br].CH 2 Cl 2 , is shown in Figure 1. One molecule of solvent dichloromethane is present in the asymmetric unit. This was refined as disordered over two positions, with occupancies of 0.81 (15):0.19 (15)..
The coordination geometry at the Re atom is a distorted octahedron with the three CO ligands arranged in a fac-fashion.
Furthermore, a kind of inter-molecular face-to-face stacking present in the molecular structure of [Re(CO) 3 (L)Br].CH 2 Cl 2 : the 1,3,4-oxadiazole moiety in one molecule is almost parallel to the other one from another complex , and the approximate distance between the two closest atoms (N2-N3) is only 3.376°. Thus a bonded dual-molecule structure is constructed in the complex molecule which is believed a rigid one and will prevent geometric relaxation effectively (Zhang et al., 2009). Such rigid structure is promised possessing excellent luminescent properties.

Experimental
The oxadiazole ligand was synthesized as follows: 5- of toluene for 6 h. After the mixture was cooled to RT, the solvent was removed in a water bath under reduced pressure. The resulting yellow solid was purified by silica gel column chromatography with acetic acid ethyl ester and dichloromethane (v/v = 10:1). Yellow single crystals of complexes 2 suitable for X-ray diffraction studies were grown from slow evaporation of a CH 2 Cl 2 solution.