Crystal structure of (E)-1-(3-benzyl-5-phenyl-1,3-thiazol-2-ylidene)-2-[(E)-1,2,3,4-tetrahydronaphthalen-1-ylidene]hydrazin-1-ium bromide

In the crystal of the title molecular salt, ion pairs are linked by C—H⋯Br and N—H⋯Br hydrogen bonds, which are connected into helical chains extending along the c-axis direction by weak, electrostatic S⋯Br− interactions.

In the title molecular salt, C 26 H 24 N 3 S + ÁBr À , the dihedral angles between the thiazole ring and its attached phenyl and benzoyl rings are 54.81 (7) and 85.51 (7) , respectively. In the crystal, ion pairs are linked by C-HÁ Á ÁBr and N-HÁ Á ÁBr hydrogen bonds and are connected into helical chains extending along the c-axis direction by weak, electrostatic SÁ Á ÁBr À interactions. A Hirshfeld surface analysis was performed, which showed the dominant role of HÁ Á ÁH contacts (51.3%).

Supramolecular features
In the crystal, the S1Á Á ÁBr1 distance of 3.5017 (7) Å is some 0.15 Å less than the sum of the van der Waals radii and likely represents an electrostatic interaction between the two atoms since S1 is near to the cationic charge. Over 200 structures having SÁ Á ÁBr À contacts of this length or shorter are present in the Cambridge Structural Database, two examples being reported by Auffinger et al. (2004) and Thompson & Richardson (1977). This interaction, together with the N2-H2Á Á ÁBr1, C10-H10BÁ Á ÁBr1, C20-H20BÁ Á ÁBr1 and C26-H26Á Á ÁBr1 hydrogen bonds (Table 1) form helical chains extending along the c-axis direction (Fig. 2). It may be noted that the same bromide ion Br1(x, 1 À y, z À 1 2 ) accepts all the identified contacts. These [001] chains pack in the other two dimensions with normal van der Waals contacts (Fig. 3), in agreement with the results of the Hirshfeld surface analysis (vide infra).

Figure 2
Detail of a supramolecular chain viewed along the a-axis direction with C-HÁ Á ÁBr and N-HÁ Á ÁBr hydrogen bonds depicted by brown dashed lines. The short BrÁ Á ÁS contact is depicted by a yellow dashed line.

Figure 3
Packing seen along the c-axis direction giving an end view of the chains. Intermolecular interactions are depicted as in Fig. 2.

Figure 1
The title molecule showing 50% probability ellipsoids. zinium bromide unknown solvate (CSD refcode BOCROC; Mague, et al., 2014) and (E)-2-[(2-nitrophenyl)methylidene]-1-[(2Z)-4-phenyl-2,3-dihydro-1,3-thiazol-2-ylidene]hydrazinium bromide (NUCLOO; Hassan et al., 2016) are the closest analogues and another similar compound is 2-{1-[(3,4diphenyl-1,3-thiazol-2(3H)-ylidene)hydrazinylidene]ethyl}pyridinium bromide monohydrate (QOCGIA; Akkurt et al., 2014). Key bond distances and angles for I and these three compounds are listed in supplementary Table 1. In the thiazole ring there is little variation except for the N-C distance c in NUCLOO, which is marginally shorter than in the others, possibly due to the nitrogen atom being unsubstituted. The most noticeable differences occur in the N-C and C N distances d and e where the difference between the two is largest in QOCGIA where the absence of the positive charge on the nitrogen atom bound to the thiazole ring leads to a greater localization of the -electron density in the C N bond.

Hirshfeld surface analysis
The Hirshfeld surface for I was calculated using Crystal Explorer17 (Turner et al., 2017)

Synthesis and crystallization
The title compound was prepared according to our previously reported method (Mohamed et al., 2013). Mono-crystals of I suitable for X-ray diffraction were obtained by recrystallization of the crude product from ethanol solution.

(E)-1-(3-Benzyl-5-phenyl-1,3-thiazol-2-ylidene)-2-[(E)-1,2,3,4-tetrahydronaphthalen-1-ylidene]hydrazin-1-ium bromide
Crystal data where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.56 e Å −3 Δρ min = −0.22 e Å −3 Absolute structure: Parsons et al. (2013) Absolute structure parameter: 0.0130 (18) 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. H-atoms attached to carbon were placed in calculated positions (C-H = 0.95 -0.99 Å) while that attached to nitrogen was placed in a location derived from a difference map and its coordinates adjusted to give N-H = 0.91 %A. All were included as riding contributions with isotropic displacement parameters 1.2 -1.5 times those of the attached atoms.