Synthesis, crystal structure and Hirshfeld surface analysis of a polymeric bismuthate(III) halide complex, (C6H6N3)2[BiCl5]·2H2O

The structure of this new halide-bridged polymer comprises polyanionic zigzag chains of formula [(BiCl5)2−]n running along the c-axis direction. The 1,2,3-benzotriazolium cations are linked between these polymer chains, via the water molecules, giving rise to left- and right-handed helical chains.

The synthesis and the crystal structure of a new halide-bridged polymer, namely catena-poly[bis (1,2,3-benzotriazolium) [[tetrachloridobismuth(III)]--chlorido] dihydrate], {(C 6 H 6 N 3 ) 2 [BiCl 5 ]Á2H 2 O} n are reported. The structure comprises polyanionic zigzag chains of formula [(BiCl 5 ) 2À ] n running along the c-axis direction. The 1,2,3-benzotriazolium cations are linked between these polymer chains, via the water molecules, giving rise to left-and right-handed helical chains. Hirshfeld surface analysis and fingerprint plots were used to decode the intermolecular interactions in the crystal network and determine the contribution of the component units for the construction of the three-dimensional architecture.

Chemical context
Bismuth-halide complexes are of contemporary interest because of their structural diversity and numerous promising physical properties such as dielectric, ferroelectric, ferroelastic, non-linear optical and thermochromism (Bator et al., 1997;Bednarska-Bolek et al., 2000;Sobczyk et al., 1997;Bator et al., 1998). Generally, in these compounds, the BiX 6 octahedra may join to form discrete (i.e. mononuclear) or extended (i.e. polynuclear) inorganic networks of corner-, edge-, or face-sharing octahedra, leading to an extensive family of bismuth halogenoanions (Jakubas, 1986;Jakubas et al., 1988Jakubas et al., , 1995. A variety of organic cations, ring shaped or linear, have a strong impact on the arrangements of BiX 6 octahedra and the formation of hydrogen bonds (Dammak et al., 2015;Elfaleh & Kamoun, 2014). This class of compounds has also attracted much attention in the field of crystal engineering over the last decade on account of their capability for the creation of extended architectures via intermolecular non-covalent binding interactions. (i.e. hydrogen bonding, ionic andstacking interactions ;Belter & Fronczek, 2013;Thirunavukkarasu et al., 2013;Aloui et al., 2015). ISSN 2056-9890 As part of our studies in this area, we chose benzotriazole, which is an aromatic heterocyclic base with three protonatable nitrogen atoms, as the organic cation.
In the extended structure of (I), adjacent BiCl 6 octahedra are connected through Cl4 and Cl4 iii so as to form [(BiCl 5 ) 2À ] n polyanionic zigzag chains propagating along the caxis direction, with the shortest intrachain BiÁ Á ÁBi distance of 5.508 (1) Å and a Cl4-Bi-Cl4 ii angle of 89.61 (3) (Fig. 2) The overall negative charges of the resulting polymers are counterbalanced by the protonated 1,2,3benzotriazolium cations (Fig. 2b). As usual, this aromatic amine is protonated at the N3 atom and the C-C, N-N and C-N bond lengths vary from 1.358 (18

Hirshfeld surface analysis
The Hirshfeld surface (Wolff et al., 2012) mapped with a d norm function for the asymmetric unit for the title compounds clearly shows the red spots derived from HÁ Á ÁO and HÁ Á ÁCl/ ClÁ Á ÁH contacts (Fig. 4) The intermolecular interactions were further evaluated by using the enrichment ratio (ER; Jelsch et al., 2014). The largest contribution to the Hirshfeld surface is from HÁ Á ÁCl/ClÁ Á ÁH contacts associated with O-HÁ Á ÁCl hydrogen bonds and their ER value is 1.73. The HÁ Á ÁH contacts are the second largest contributor, but they display an enrichment ratio significantly below unity (ER HH = 0.47). The formation of extensiveinteractions is reflected in the relatively high ER CC of 3.94.

Synthesis and crystallization
The title compound was prepared by dropwise addition of an ethanolic solution of 1H-benzotriazole (0.061 g, 0.5 mmol) to Hirshfeld surface mapped over d norm of (I).

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 3 Two-dimensional fingerprint plots for (I) showing contributions from different contacts.

catena-Poly[bis(1,2,3-benzotriazolium) [[tetrachloridobismuth(III)]-µ-chlorido] dihydrate]
Crystal data (C 6  Extinction correction: SHELXL97 (Sheldrick, 2008), Fc * =kFc[1+0.001xFc 2 λ 3 /sin(2θ)] -1/4 Extinction coefficient: 0.0028 (4) Absolute structure: Flack (1983), 731 Friedel pairs Absolute structure parameter: −0.036 (14) 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.