Bis(5-bromopyridine-2-carboxylato-κO)triphenylantimony(V)

In the title compound, [Sb(C6H5)3(C6H3BrNO2)2], the Sb center has a distorted trigonal–bipyramidal geometry, with two carboxylate O atoms of two 5-bromopyridine-2-carboxylate ligands in equatorial positions and three phenyl ligands in axial positions. The crystal structure is stabilized by C—H⋯Br hydrogen bonds and intermolecular C—Br⋯π interactions [C⋯π = 3.57 (1) Å].

As shown in Fig. 1, the Sb atom is five-coordinated by the three phenyl C atoms and the two carboxylate O atoms. The average distance of Sb-C (2.10 Å) in the (I) is shorter than the average distance of S-C (2.225 Å; Mahon et al., 1998).
The average distance of  in the (I) is equal to the average distance of Sb-O (2.145 Å;Chaudhari et al., 2007). The crystal structure is stabilized by intermolecular C-H···Br hydrogen bonds ( Fig. 2 and Table 1; symmetry code as in Fig. 2). In addition, the crystal structure exhibits C-Br···π interactions, with a C5-Br···Cg ii separation of 3.57 (1) Å ( Fig. 2; Cg is the centroid of the C7-C12 benzene ring, symmetry code as in Fig. 2).

S2. Experimental
5-bromopyridine-2-carboxylic acid (0.061 g, 0.3 mmol) and sodium methoxide (0.6 ml, 0.3 mmol) was added to a stirring solution containing triphenylantimonydichloride (0.064 g, 0.15 mmol) in toluene (25 ml). After refluxing for 8 h, the colorless solution was obtained and then filtered. The solvent was gradually removed by evaporation under vacuum until the white solid is obtained. The solid was recrystallized from petroleum ether/dichoromethane (1:1) to give colorless crystals.

S3. Refinement
All H atoms were positioned geometrically and refined as riding atoms, with C-H = 0.93 Å, Uiso(H) = 1.2Ueq(C).  The molecular structure of the title compound, showing displacement ellipsoids drawn at the 30% probability level.

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. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > 2sigma(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.