4-[(5-Bromo-2-hy­droxy­benzyl­idene)amino]-3-ethyl-1H-1,2,4-triazole-5(4H)-thione

Cai-Xia Yuan; Shu-Fen Lan; Xin-Yu Liu; Miao-Li Zhu

doi:10.1107/S1600536814016833

. 2014 Jul 26;70(Pt 8):o881–o882. doi: 10.1107/S1600536814016833

4-[(5-Bromo-2-hydroxybenzylidene)amino]-3-ethyl-1H-1,2,4-triazole-5(4H)-thione

Cai-Xia Yuan ^a, Shu-Fen Lan ^a, Xin-Yu Liu ^a, Miao-Li Zhu ^a,^*

PMCID: PMC4158482 PMID: 25249924

Abstract

The title compound, C₁₁H₁₁BrN₄OS, crystallized as a racemic twin with two symmetry-independent molecules in the asymmetric unit. The dihedral angles between the benzene and triazole rings of the two independent molecules are 56.41 (18) and 54.48 (18)°. An intramolecular O—H⋯N hydrogen bond occurs in each molecule. In the crystal, pairs of symmetry-independent molecules are linked by pairs of almost linear N—H⋯S hydrogen bonds, forming cyclic dimers characterized by an R ₂ ²(8) motif. There are weak π–π interactions between the benzene rings of symmetry-independent molecules, with a centroid–centroid distance of 3.874 (3) Å.

Keywords: crystal structure

Related literature

For background to the biological activity of related compounds, see: Demirbas (2004 ▶); Demirbas et al. (2009 ▶); Todoulou et al. (1994 ▶); Kumar et al. (2008 ▶); Kochikyan et al. (2011 ▶); Singhal et al. (2011 ▶); Popiołek et al. (2013 ▶); Sraa (2012 ▶). For similar structures, see: Wu et al. (2012 ▶); Pannu & Hundal (2011 ▶). For standard bond lengths, see: Allen et al. (1987 ▶). For graph-sets of hydrogen-bond motifs, see: Bernstein et al. (1995 ▶).

Experimental

Crystal data

C₁₁H₁₁BrN₄OS
M _r = 327.21
Monoclinic,
a = 6.323 (4) Å
b = 16.459 (11) Å
c = 12.461 (8) Å
β = 90.330 (9)°
V = 1296.8 (15) Å³
Z = 4
Mo Kα radiation
μ = 3.32 mm⁻¹
T = 298 K
0.40 × 0.35 × 0.30 mm

Data collection

Bruker SMART APEXII diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 2000 ▶) T _min = 0.350, T _max = 0.435
14802 measured reflections
5222 independent reflections
4285 reflections with I > 2σ(I)
R _int = 0.033

Refinement

R[F ² > 2σ(F ²)] = 0.031
wR(F ²) = 0.065
S = 1.01
5222 reflections
328 parameters
1 restraint
H-atom parameters constrained
Δρ_max = 0.28 e Å⁻³
Δρ_min = −0.45 e Å⁻³
Absolute structure: Flack (1983 ▶), 2514 Friedel pairs
Absolute structure parameter: 0.581 (7)

Data collection: SMART (Bruker, 2000 ▶); cell refinement: SAINT (Bruker, 2000 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL/PC (Sheldrick, 2008 ▶); software used to prepare material for publication: SHELXTL/PC.

Supplementary Material

Crystal structure: contains datablock(s) I. DOI: 10.1107/S1600536814016833/fy2115sup1.cif

e-70-0o881-sup1.cif^{(29.9KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536814016833/fy2115Isup2.hkl

e-70-0o881-Isup2.hkl^{(255.7KB, hkl)}

Click here for additional data file.^{(4.8KB, cml)}

Supporting information file. DOI: 10.1107/S1600536814016833/fy2115Isup3.cml

CCDC reference: 1015277

Additional supporting information: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1⋯S2ⁱ	0.86	2.45	3.309 (3)	176
N5—H5A⋯S1ⁱⁱ	0.86	2.44	3.302 (3)	177
O1—H1A⋯N4	0.82	2.02	2.712 (4)	141
O2—H2⋯N8	0.82	1.99	2.695 (4)	143

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Symmetry codes: (i) Inline graphic ; (ii) .

Acknowledgments

The authors acknowledge the National Natural Science Foundation of China (grant Nos. 21001070 and 21271121) and the Province Natural Science Foundation of Shanxi Province of China (grant No. 2011021006–2).

supplementary crystallographic information

S1. Comment

Recently, 1,2,4-triazoles and their derivatives have been the focus of a great deal of attention owing to their effective biological activities such as antimicrobial, antiviral, analgesic, anti-inflammatory, anticancer and antioxidant properties (Demirbas et al., 2004 and 2009; Kochikyan et al., 2011; Kumar et al., 2008; Singhal et al., 2011; Todoulou et al., 1994). As a result, a number of attempts were made to improve the activity of these compounds by varying the substituents on the 1,2,4-triazole nucleus (Popiołek et al., 2013; Sraa et al., 2012). Among these, the amino- and mercapto-group substituted 1,2,4-triazole ring systems represent an important group of compounds that are promising for practical application. Therefore, the title compound (I), has been synthesized and its crystal structure has been determinined.

The crystal structure is illustrated in Fig. 1. The title compound (I) crystallizes in the monoclinic space group P2₁ with two symmetry-independent molecules in the unit cell. The bond lengths of N4–C5 [1.274 (5) Å] and N8–C16 [1.272 (5) Å] confirm them as double bonds, which is similar to those reported in other Schiff bases (Pannu et al., 2011; Wu et al., 2012;). The molecule of (I) exists in the thione tautometic form, with C═S distances of 1.673 (4) and 1.672 (4) Å, which indicates a substantial double-bond character (Allen et al., 1987).

The packing arrangement in the crystal structure of (I) is shown in Fig. 2. As a common feature of o-hydroxysalicylidene systems, the azomethine group in title compound forms intramolecular O–H···N hydrogen bonds with the neighbouring hydroxyl groups. Moreover, the crystal structure also contains intermolecular N–H···S hydrogen bonds between both independent molecules with cyclic motifs [graph set R₂²(8)] (Bernstein et al., 1995). The molecules are further linked via weak π-π interactions between benzene rings (Cg1 and Cg2). The hydrogen bonds and π-π interactions link the molecules into ribbon structures.

S2. Experimental

The title compound was synthesized by condensation of 4-amino-3-ethyl- 1H-1,2,4-triazole-5(4H)-thione and 5-Br-salicylaldehyde. 0.5 mmol of 4-amino-3-ethyl-1,2,4-triazole-5-thione was thoroughly dissolved in 20 ml of ethanol with a constant stirring at 353 K. Then 0.5 mmol of 5-bromosalicylaldehyde in 10 ml ethanol was added dropwise to a solution of the above. The mixture was further refluxed for 2 h. The resulting yellow solution was filtered and the filtrate was left to stand at room temperature. The yellow crystals of compound (I) were received from the filtrate with slowly evaporating the solvent for a few days. Yield: 78%. Anal. Calcd. for C₁₁H₁₁BrN₄OS: C 40.38, H 3.39, N 17.12%. Found: C 40.31, H 3.45, N 17.07%. IR (ν/cm^-1): 3109, 3055, 2958, 1603, 1588, 1513, 1416, 1352, 1288, 1165, 1174, 967, 817, 627. UV/vis in DMSO, λ_max/nm (ε 10³/M^-1 cm^-1): 265(13.9), 343(7.77).