3,6-Bis(3,4,5-trimethoxy­phen­yl)-1,2,4-triazolo[3,4-b][1,3,4]thia­diazole

Hai-Tang Du; Hai-Jun Du; Weiyi Zhou

doi:10.1107/S1600536808022502

. 2008 Jul 23;64(Pt 8):o1577. doi: 10.1107/S1600536808022502

3,6-Bis(3,4,5-trimethoxyphenyl)-1,2,4-triazolo[3,4-b][1,3,4]thiadiazole

Hai-Tang Du ^a,^*, Hai-Jun Du ^b, Weiyi Zhou ^c

PMCID: PMC2962044 PMID: 21203276

Abstract

In the molecule of the title compound, C₂₁H₂₂N₄O₆S, the planar central heterocyclic ring system is oriented with respect to the trimethoxyphenyl rings at dihedral angles of 2.60 (5) and 3.60 (6)°. Intramolecular C—H⋯N and C—H⋯S hydrogen bonds result in the formation of planar five- and six-membered rings. In the crystal structure, intermolecular C—H⋯O hydrogen bonds link the molecules. There is a C—H⋯π contact between a methyl group and a trimethoxyphenyl ring, and a π–π contact between the central heterocyclic ring system and a trimethoxyphenyl ring [centroid–centroid distance = 3.640 (1) Å].

Related literature

For general background, see: Karabasanagouda et al. (2007 ▶); Mathew et al. (2007 ▶).

Experimental

Crystal data

C₂₁H₂₂N₄O₆S
M _r = 458.49
Triclinic,
a = 8.6762 (17) Å
b = 8.9289 (18) Å
c = 13.735 (3) Å
α = 94.50 (3)°
β = 90.82 (3)°
γ = 90.47 (3)°
V = 1060.6 (4) Å³
Z = 2
Mo Kα radiation
μ = 0.20 mm⁻¹
T = 113 (2) K
0.22 × 0.20 × 0.10 mm

Data collection

Rigaku Saturn CCD area-detector diffractometer
Absorption correction: multi-scan (CrystalClear; Rigaku/MSC, 2005 ▶) T _min = 0.957, T _max = 0.980
6899 measured reflections
3720 independent reflections
3102 reflections with I > 2σ(I)
R _int = 0.022

Refinement

R[F ² > 2σ(F ²)] = 0.044
wR(F ²) = 0.137
S = 1.19
3720 reflections
295 parameters
H-atom parameters constrained
Δρ_max = 0.93 e Å⁻³
Δρ_min = −0.56 e Å⁻³

Data collection: CrystalClear (Rigaku/MSC, 2005 ▶); cell refinement: CrystalClear; data reduction: CrystalStructure (Rigaku/MSC, 2005 ▶); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL (Sheldrick, 2008 ▶); software used to prepare material for publication: SHELXTL.

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536808022502/hk2498sup1.cif

e-64-o1577-sup1.cif^{(22.9KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808022502/hk2498Isup2.hkl

e-64-o1577-Isup2.hkl^{(182.4KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

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

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C2—H2⋯N4	0.93	2.36	3.047 (3)	130
C14—H14⋯S1	0.93	2.72	3.130 (3)	108
C19—H19B⋯O3ⁱ	0.96	2.53	3.384 (2)	148
C21—H21B⋯O1ⁱⁱ	0.96	2.43	3.331 (3)	156
C19—H19C⋯Cg3ⁱⁱⁱ	0.96	3.30	4.057 (3)	137

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) . Cg3 is the centroid of the trimethoxyphenyl ring C1–C6.

Acknowledgments

The authors thank Guiyang College (grant No. 2008012) for financial support.

supplementary crystallographic information

Comment

1,2,4-Triazole and 1,3,4-thiadiazole represent one of the most biologically active classes of compounds, possessing a wide spectrum of activities. Various substituted 1,2,4-triazolo[3,4-b]-1,3,4-thiadiazoles are associated with diverse pharmacological activities such as antimicrobial (Karabasanagouda et al., 2007) and anti-inflammatory activity (Mathew et al., 2007). We report herein the crystal structure of the title compound.

In the molecule of the title compound (Fig. 1) the bond lengths and angles are within normal ranges. Rings A (C1-C6), B (N1-N3/C10/C11), C (S1/N3/N4/C11/C12) and D (C13-C18) are, of course, planar, and the dihedral angles between them are A/B = 3.42 (6)°, A/C = 1.96 (5)°, A/D = 4.76 (5)°, B/C = 1.65 (6)°, B/D = 3.91 (6)° and C/D = 3.42 (5)°. So, the rings are nearly coplanar. The intramolecular C-H···N and C-H···S hydrogen bonds (Table 1) result in the formation of planar six- and five-membered rings E: (N3/N4/C1/C2/C10/H2) and F (S1/C12-C14/H14), in which they are oriented with respect to the planar central heterocylic ring system at dihedral angles of 1.56 (5)° and 4.00 (5)°, respectively.

In the crystal structure, intermolecular C-H···O hydrogen bonds (Table 1) link the molecules (Fig. 2), in which they may be effective in the stabilization of the structure. A C—H···π contact (Table 1) between the trimethoxyphenyl ring and the methyl group and a π—π contact between B and D rings Cg2···Cg4ⁱ [symmetry code: (i) 1 - x, 1 - y, -z, where Cg2 and Cg4 are centroids of the rings B (N1-N3/C10/C11) and D (C13-C18), respectively] further stabilize the structure, with centroid-centroid distance of 3.640 (1) Å.

Experimental

For the preparation of the title compound, 4-amino-5-(3,4,5-trimethoxyphenyl) -4H-1,2,4-triazole-3-thiol (0.01 M) and 3,4,5-trimethoxybenzoic acid (0.01 M) were dissolved in dry phosphorous oxychloride (10 ml). The resulted solution was further heated under reflux for 7 h. The reaction mixture was cooled to room temperature and the mixture was gradually poured onto crushed ice with stirring. Finally, powdered potassium carbonate and the required amount of solid potassium hydroxide were added until the pH of the mixture was raised to 8, to remove the excess of phosphorous oxychloride. The mixture was allowed to stand overnight and the solid was separated. It was filtered, washed with cold water, and then dried. Crystals suitable for X-ray analysis were obtained by the recrystallization of the solid residue from a mixture of N,N-dimethyl- formamide/ethanol (1:1) by slow evaporation at room temperature.