Bis(5-amino-2-chlorobenzoato-κO)triphenylantimony(V)

In the title compound, [Sb(C6H5)3(C7H5ClNO2)2], the Sb center has a distorted trigonal-bipyramidal geometry, with the O atoms of two carboxylate groups in axial positions and the C atoms of the phenyl groups in equatorial positions. Intramolecular C—H⋯O interactions occur. The molecules are connected by intermolecular N—H⋯O, N—H⋯N and C—H⋯O hydrogen-bonding interactions and C—H⋯π stacking interactions, forming a three-dimensional supramolecular framework

In the title compound, [Sb(C 6 H 5 ) 3 (C 7 H 5 ClNO 2 ) 2 ], the Sb center has a distorted trigonal-bipyramidal geometry, with the O atoms of two carboxylate groups in axial positions and the C atoms of the phenyl groups in equatorial positions. Intramolecular C-HÁ Á ÁO interactions occur. The molecules are connected by intermolecular N-HÁ Á ÁO, N-HÁ Á ÁN and C-HÁ Á ÁO hydrogen-bonding interactions and C-HÁ Á Á stacking interactions, forming a three-dimensional supramolecular framework

S1. Comment
Recently, the chemistry of antimony complexes derived from carboxylates has become an active area of research due to the biological perspective and their versatile bonding modes, the striking structural possibilities ranging from discrete monomeric structures to supramolecular assemblies (Yin et al. 2009). As a part of our ongoing investigations in ths field we have synthesized the title compound and determined its crystal structure. As is shown in Fig. 1, the central antimony atom is five-coordinated with a slightly distorted trigonal bipyramidal geometry. Around the central Sb1 atom, C15, C21 and C27 occupy the equatorial plane, while O1 and O3 lie in axial sites. The Sb-O bond distances (Sb1-O1 = 2.137 (3) Å; Sb1-O3 = 2.125 (3) Å) ( Table 1) are comparable to those found in organoantimony arylhydroxmates (Wang et al. 2005). The Sb-C bond distances (Sb1-C15 = 2.108 (5) Å; Sb1-C21 = 2.098 (5) Å; Sb1-C27 = 2.109 (5) Å) of the compound lie within the normal range for Sb-C (phenyl) bonds (2.10-2.13 Å). The supramolecular structure of the title compound results from intermolecular C-H···O, N-H···O and N-H···N hydrogen-bonding interactions and C-H···Π stacking interactions (Fig. 2, Table 2) assembling the molecules into a three-dimensional supramolecular frameworks

S2. Experimental
The reaction was carried out under nitrogen atmosphere. 5-Amino-2-chlorobenzoic acid (1 mmol) and sodium ethoxide (1.2 mmol) were added to a stirred solution of methanol (30 ml) in a Schlenk flask and stirred for 0.5 h. Triphenylantimony dichloride (0.5 mmol) was then added to the reactor and the reaction mixture was stirred for 12 h at room temperature. The resulting clear solution was evaporated under vacuum. The product was crystallized from a mixture of ether/n-hexane (1:1) to yield colourless blocks of the title compound (yield 80%

S3. Refinement
The N-bound H atoms were located in a difference Fourier map. In the refinement process the N-H bond lengths were restrained to 0.85 (2) Å and isotropic displacement parameters of these H atoms were freely refined. Other H atoms were positioned geometrically, with C-H = 0.93 Å and refined with a riding model; U iso (H) = 1.2 U eq (C).  The molecular structure of the compound, showing 50% probability displacement ellipsoids. H atoms have been omitted for clarity.

Figure 2
View of the three-dimensional supramolecular network structure in the title compound.