1-Benzothio­phene-2-carbaldehyde 4-ethyl­thio­semicarbazone

Safa’a Fares Kayed; Yang Farina; Jim Simpson

doi:10.1107/S1600536808042797

. 2008 Dec 20;65(Pt 1):o180–o181. doi: 10.1107/S1600536808042797

1-Benzothiophene-2-carbaldehyde 4-ethylthiosemicarbazone

Safa’a Fares Kayed ^a, Yang Farina ^a,^*, Jim Simpson ^b

PMCID: PMC2968090 PMID: 21581636

Abstract

The title compound, C₁₃H₁₅N₃S₂, crystallizes with two unique molecules, A and B, in the asymmetric unit. These differ principally in that the methyl group of the 4-ethylthiosemicarbazone moiety is ordered in molecule A but disordered over two positions with equal occupancies in molecule B. The benzothiophene group and the semicarbazone unit are inclined at dihedral angles of 11.78 (8)° for molecule A and 8.18 (13)° for molecule B. Weak intramolecular N—H⋯N interactions contribute to the planarity of the semicarbazone units in both molecules and each molecule adopts an E configuration with respect to the C=N bonds. In the crystal structure, molecules form centrosymmetric dimers as a result of N—H⋯S hydrogen bonds, augmented by C—H⋯S interactions for molecule A and C—H⋯S interactions for molecule B. Weak C—H⋯π interactions stack the dimers of both molecules into columns down the a axis.

Related literature

For background to the biological activity of thiosemicarbazones, see: de Sousa et al. (2007 ▶). For related structures, see: Chuev et al. (1992 ▶); de Lima et al. (2002 ▶); Isik et al. (2006 ▶); Kayed et al. (2008 ▶). For details of graph-set analysis of hydrogen-bonding patterns, see: Bernstein et al. (1995 ▶). For reference structural data, see: Allen et al. (1987 ▶).

Experimental

Crystal data

C₁₃H₁₅N₃S₂
M _r = 277.40
Triclinic,
a = 5.5343 (5) Å
b = 10.9943 (10) Å
c = 23.443 (2) Å
α = 78.825 (5)°
β = 88.175 (5)°
γ = 76.298 (5)°
V = 1359.4 (2) Å³
Z = 4
Mo Kα radiation
μ = 0.38 mm⁻¹
T = 92 (2) K
0.37 × 0.10 × 0.05 mm

Data collection

Bruker APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2006 ▶) T _min = 0.873, T _max = 0.981
18044 measured reflections
5907 independent reflections
4307 reflections with I > 2σ(I)
R _int = 0.051

Refinement

R[F ² > 2σ(F ²)] = 0.042
wR(F ²) = 0.111
S = 1.05
5907 reflections
354 parameters
6 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.49 e Å⁻³
Δρ_min = −0.41 e Å⁻³

Data collection: APEX2 (Bruker 2006 ▶); cell refinement: APEX2 and SAINT (Bruker 2006 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶) and TITAN (Hunter & Simpson, 1999 ▶); molecular graphics: SHELXTL (Sheldrick, 2008 ▶) and Mercury (Macrae et al., 2006 ▶); software used to prepare material for publication: SHELXL97, enCIFer (Allen et al., 2004 ▶), PLATON (Spek, 2003 ▶) and publCIF (Westrip, 2009 ▶).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536808042797/ci2731sup1.cif

e-65-0o180-sup1.cif^{(26.5KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808042797/ci2731Isup2.hkl

e-65-0o180-Isup2.hkl^{(289.2KB, 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
N3A—H3NA⋯N1A	0.84 (1)	2.27 (2)	2.623 (3)	106 (2)
N3B—H3NB⋯N1B	0.83 (1)	2.26 (2)	2.627 (3)	107 (2)
C10A—H10A⋯S2Aⁱ	0.98	2.84	3.374 (2)	115
N2A—H2NA⋯S2Aⁱ	0.85 (1)	2.81 (1)	3.638 (2)	164 (2)
C10B—H10D⋯S2Bⁱⁱ	0.98	2.82	3.373 (2)	117
C10A—H10B⋯Cg1ⁱⁱⁱ	0.98	2.71	3.577 (2)	147
C10B—H10E⋯Cg2^iv	0.98	2.72	3.600 (2)	150

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) ; (iv) . Cg1 and Cg2 are the centroids of the S1A/C1A/C2A/C3A/C8A and S1B/C1B/C2B/C3B/C8B rings, respectively.

Acknowledgments

The authors thank the Universiti Kebangsaan Malaysia and the Ministry of Higher Education, Malaysia, for supporting this research through grants UKM-ST-01-FRGS0022–2006 and UKM-GUP-NBT-08–27-112. The authors also thank the University of Otago for purchase of the diffractometer.

supplementary crystallographic information

Comment

Thiosemicarbazones are a class of compounds that have been investigated because of their biological activity (de Sousa et al., 2007). As a continuation of our work on thiosemicarbazone compounds as potential ligands in transition metal chemistry (Kayed et al., 2008;) we report here the structure of the title compound (Fig. 1), which crystallizes with two unique molecules, A and B, in the asymmetric unit. The two molecules are closely similar with the exception of the methyl C atom of the ethyl group which is disordered over two positions C131 and C132, with equal occupancies. The similarities of the remainder of the two molecules are demonstrated by the fact that the non-hydrogen atoms of molecules A and B overlay in Mercury (Macrae et al., 2006) with an r.m.s. deviation of 0.077 Å, when the C132 disorder component is excluded. The molecules are each reasonably planar with r.m.s. deviations of 0.137 Å and 0.128 Å from the planes through all non-hydrogen atoms of the two molecules excluding the C132 disorder component. The planarity of the N1/N2/C11/S2/N3 segments of both molecules (r.m.s. deviations 0.050 Å for molecule A and 0.037 Å for molecule B) is aided by weak intramolecular N3—H3N···N1 interactions. The benzothiophene groups and the semicarbazone groups are inclined at dihedral angles of 11.78 (8)° for molecule A and 8.18 (13)° for molecule B. Both molecules adopt an E configuration with respect to the C═N bonds, bond distances are normal (Allen et al., 1987) and comparable to those in similar structures (Chuev et al. 1992; de Lima et al. 2002; Isik et al. 2006; Kayed et al. 2008).

In the crystal structure, a centrosymmetric dimer with an R²₂(8) ring motif (Bernstein et al., 1995) is formed by through N2A—H2NA···S2A hydrogen bonds strengthened by additional C10A—H10A···S2A interactions for molecule A. A second dimer forms via C10B—H10D···S2B interactions for molecule B (Table 1 and Fig. 2). The dimers are further aggregated into columns down the a axis by weak C—H···π interactions involving the C10A and C10B methyl groups and the thiophene rings of adjacent molecules, Fig. 3.

Experimental

The title compound was prepared by heating 35 ml of an ethanolic solution of 2-acetylbenzothiophene (1.76 g, 10 mmol) and 4-ethyl-3-thiosemicarbazide (1.2 g, 10 mmol) under reflux for 2 h. Three drops of concentrated H₂SO₄ were added. The resulting product was isolated and recrystallized from acetonitrile to afford yellow needles of the title compound in 63.5% yield (m.p. 448–450 K).