catena-Poly[bis(1,3-benzothiazol-3-ium) [[dichloridoantimonate(III)]-di-μ-chlorido-μ-oxido-[chloridoantimonate(III)]-μ-chlorido]]

In the crystal, alternating layers and chains of the organic cations and inorganic anions are connected through an extensive three-dimensional network of N—H⋯Cl and C—H⋯Cl hydrogen bonds.π–π stacking interactions link the molecules within the layers and also link the layers together and reinforce the cohesion of the ionic structure.

The title compound, {(C 7 H 6 NS) 2 [Sb 2 Cl 6 O]} n , contains two benzothiazolidium cations and one tri--chlorido-trichlorido--oxido-diantimonate(III) anion. The structure of the inorganic cation may be described as as being built up from two polyhedra, i.e. a square-pyramidal SbCl 4 O and a distorted octahedral SbOCl 5 unit, sharing a common face (comprising the O atom and two Cl atoms). The two benzothiazole cations are quasi-planar and subtend a dihedral angle of 19.93 (5) . The crystal packing can be described by alternating (100) layers and [001] chains of the organic cations and inorganic anions connected through an extensive three-dimensional network of N-HÁ Á ÁCl, C-HÁ Á ÁO and C-HÁ Á ÁCl hydrogen bonds. This is consolidated by slippedstacking, with centroid-tocentroid distances between the benzothiazole rings of 3.7111 (18)-3.8452 (16) Å . These interactions link the molecules within the layers and also link the layers together and reinforce the cohesion of the ionic structure.

Chemical context
The coordination chemistry of antimony has both a practical and theoretical interest (Abboud et al., 2007;Bujak & Angel, 2006). Recently, the use of antimony complexes in cancer chemotherapy has become a topic of interest (Demicheli et al., 2006;Rais et al., 2000). As part of our ongoing studies of benzothiazole-based coordination networks (Bouchareb et al., 2014), we now report the polymeric structure of new organicinorganic hybrid compound {(C 7 H 6 NS) 2 [Sb 2 Cl 6 O]} n , (I).
The structure of the inorganic anion may be described as two polyhedra, square-pyramidal SbCl 4 O and distorted octahedral SbOCl 5 , sharing a common face (O1, Cl5 and Cl6). In the first polyhedron, four Cl atoms (Cl3-Cl4-Cl5-Cl6) form a basal plane with the Sb1 atom lying 0.3011 (2) Å below the plane. The apical position is occupied by the O1 atom. In the second polyhedron, the O1 atom occupies the apical position and four Cl atoms (Cl1-Cl2-Cl5-Cl6) form the base equatorial plane with Sb2 displaced by 0.4168 (1) Å from it. The geometry of the Sb2 atom can be described as distorted octahedral, a sixth coordination is observed at a longer distance, with Sb2 coordinated by the adjacent Cl3 i atom at a distance of 3.546 (4) Å [symmetry code: (i) 1 2 À x, 1 2 + y, 1 2 À z], forming an infinite chain parallel to [001] (Fig. 2). This distance is significantly shorter than the sum of the relevant van der Waals radii of 4.01 Å (rSb = 2.1 Å and rCl = 1.91 Å ) and in good agreement with those found in [SbCl 3 (C 25 H 22 O 2 P 2 )] (Razak et al., 1999) and in [(CH 3 ) 2 NH(CH 2 ) 2 NH 3 ][SbCl 5 ] (Bujak & Angel, 2006). In this molecule, the angle between the two equatorial planes is 75.86 (2) .

Figure 1
The asymmetric unit of (I), showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level.

Figure 3
Part of diagram packing of the title compound, viewed along the a axis, showing alternating chains and layers connected by N-HÁ Á ÁCl and C-HÁ Á ÁCl hydrogen bonds (shown as dashed lines).

Synthesis and crystallization
A solution of SbCl 3 (45.6 mg, 0.2 mmol) in water (10 ml) was added dropwise to a solution of benzothiazole (0.5 ml, 4.6 mmol) in ethanol (10 ml). The mixture was then refluxed with stirring for 3 h and the resulting solution was left to stand at room temperature. Colorless crystals were obtained after several days.

catena-Poly[1,3-benzothiazol-3-ium [[dichloridoantimonate(III)]-di-µ-chlorido-µoxido-[chloridoantimonate(III)]-µ-chlorido]]
Crystal data where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max = 0.001 Δρ max = 0.54 e Å −3 Δρ min = −0.77 e Å −3 Special details Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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 > σ(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.