5-[(E)-(2-Hy­droxy­benzyl­idene)amino]-1H-1,3-benzimidazole-2(3H)-thione

Zishan Tabassum; Othman Sulaiman; Mohd Afzal; Madhukar Hemamalini; Hoong-Kun Fun

doi:10.1107/S160053681005172X

. 2010 Dec 18;67(Pt 1):o144–o145. doi: 10.1107/S160053681005172X

5-[(E)-(2-Hydroxybenzylidene)amino]-1H-1,3-benzimidazole-2(3H)-thione

Zishan Tabassum ^a, Othman Sulaiman ^a, Mohd Afzal ^b, Madhukar Hemamalini ^c, Hoong-Kun Fun ^c,^*,^‡

PMCID: PMC3050258 PMID: 21522653

Abstract

There are two molecules in the asymmetric unit of the title compound, C₁₄H₁₁N₃OS. In each, the benzimidazole ring system is essentially planar, with maximum deviations of 0.010 (2) and 0.006 (2) Å, and makes dihedral angles of 8.70 (9) and 13.75 (8)°, respectively, with the hydroxy-substituted benzene rings. Each molecule adopts an E configuration about the central C=N double bond. In the crystal, the two independent molecules are connected via intermolecular N—H⋯S hydrogen bonds, forming dimers. Furthermore, the dimers are connected by N—H⋯O hydrogen bonds into molecular ribbons along the c axis. There is an intramolecular O—H⋯N hydrogen bond in each molecule, which generates an S(6) ring motif.

Related literature

For applications of benzimidazole compounds, see: Grassmann et al. (2002 ▶); White et al. (2004 ▶); Demirayak et al. (2002 ▶). For hydrogen-bond motifs, see: Bernstein et al. (1995 ▶).

Experimental

Crystal data

C₁₄H₁₁N₃OS
M _r = 269.32
Monoclinic,
a = 8.2680 (2) Å
b = 28.1043 (6) Å
c = 10.5047 (2) Å
β = 92.234 (1)°
V = 2439.08 (9) Å³
Z = 8
Mo Kα radiation
μ = 0.26 mm⁻¹
T = 296 K
0.44 × 0.28 × 0.05 mm

Data collection

Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2009 ▶) T _min = 0.894, T _max = 0.986
27759 measured reflections
7101 independent reflections
4852 reflections with I > 2σ(I)
R _int = 0.064

Refinement

R[F ² > 2σ(F ²)] = 0.063
wR(F ²) = 0.140
S = 1.06
7101 reflections
367 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.53 e Å⁻³
Δρ_min = −0.37 e Å⁻³

Data collection: APEX2 (Bruker, 2009 ▶); cell refinement: SAINT (Bruker, 2009 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009 ▶).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S160053681005172X/rz2535sup1.cif

e-67-0o144-sup1.cif^{(22.2KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S160053681005172X/rz2535Isup2.hkl

e-67-0o144-Isup2.hkl^{(340.5KB, 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
N1A—H1NA⋯S1Bⁱ	0.86 (3)	2.61 (3)	3.4714 (19)	173 (3)
N2A—H2NA⋯O1Bⁱⁱ	0.86 (3)	1.99 (3)	2.781 (2)	153 (3)
N1B—H1NB⋯O1Aⁱⁱⁱ	0.87 (2)	2.16 (2)	2.936 (2)	149 (2)
N2B—H2NB⋯S1A^iv	0.84 (3)	2.45 (3)	3.2547 (19)	163 (2)
O1B—H1OB⋯N3B	0.99 (4)	1.64 (3)	2.552 (2)	152 (3)
O1A—H1OA⋯N3A	0.99 (4)	1.72 (4)	2.600 (3)	147 (3)

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

Acknowledgments

MA would like to thank the UGC New Delhi [grant No. F.No.31-100/2005 (SR)] and ZT thanks Universiti Sains Malaysia (USM) for the University Grant No. (1001/PTEKIND/8140152). HKF and MH thank the Malaysian Government and Universiti Sains Malaysia for the Research University Grant No. 1001/PFIZIK/811160. MH also thanks Universiti Sains Malaysia for a post-doctoral research fellowship.

supplementary crystallographic information

Comment

Benzimidazole and its derivatives are very important for the development of molecules of pharmaceutical and biological interest. Schiff bases play an important role in bioorganic chemistry as they exhibit remarkable antihistamine (Grassmann et al., 2002), antitumour (White et al., 2004) and potential anticancer activities (Demirayak et al., 2002). In view of their importance in the field of drug discovery, the crystal structure determination of the title compound was carried out and the results are presented here.

The asymmetric unit of title compound which contains two molecules [A & B] is shown in Fig. 1. All geometrical parameters are within normal ranges. Each molecule adopts an E configuration about the central C═N double bond. For both molecules, the benzimidazole ring systems (N1A–N2A/C1A–C7A)/(N1B–N2B/C1B–C7B) are essentially planar with a maximum deviation of 0.010 (2) and 0.006 (2) Å, respectively, for atom C7A and C3B. The dihedral angles between the benzimidazole ring system ((N1A–N2A/C1A–C7A)/(N1B–N2B/C1B–C7B) with the hydroxy substituted benzene ring (C9A–C14A)/(C9B–C14B) are 8.70 (9)° and 13.75 (8)° respectively.

In the crystal structure (Fig. 2), the two independent molecules are connected via intermolecular N—H···S hydrogen bonds to form dimers (Table 1). Furthermore, the dimers are connected via N—H···O hydrogen bonds to form molecular ribbons along the c-axis. There is an intramolecular N—H···O hydrogen bond which generates an S(6) (Bernstein et al., 1995) ring motif in each molecule.

Experimental

The title compound was synthesized by adding salicyaldehyde (0.122 g, 1 mmol; Alfa Aesar) to a stirred methanolic solution (20 ml) of 5-amino-2-mercaptobenzimidazole (0.165g, 1mmol; Sigma) in a 1:1 molar ratio. The reaction mixture was stirred for half an hour at room temperature. The yellow precipitate which formed was filtered off under vaccum, washed thoroughly with ice-cold methanol and dried in vacuo over anhydrous CaCl₂ (yield: 73%). Single crystals suitable for X–ray diffraction analysis were obtained from recrystallisation of the Schiff Base in a mixture of DMF:ethanol (95:5 v/v). M. p, 456–458K. Anal. Calcd. for C₁₄H₁₁N₃SO (%) C, 62.44; H, 4.11; N, 15.61, Found: C, 62.48; H, 4.12; N, 15.12. IR (KBr, cm^-1) 3170 ν (N–H), 3060 ν(O–H), 2364 ν(S–H), 1608 ν(HC═N), 1485 ν(C–N), 747 ν(C–S), UV-vis (ν_max, nm) in DMF: 320nm; 353nm. ¹H NMR (400MHz, DMSO-d₆, δ, ppm): 8.96 (1H, s, HC═N), 13.19 (1H, s, OH), 6.93–6.97 (2H, m, ArH), 7.17–7.40 (4H, m, ArH), 7.62–7.64 (1H, d, ArH) 3.38 (1H, s, SH), 12.62 (z1H, d, NH), ¹³C NMR (100MHz, DMSO–d₆, δ, ppm): 169.53, 162.53, 160.73, 143.41, 133.60, 133.27, 132.90, 131.97, 119.77, 119.39, 117.36, 116.93, 110.23, 102.07, 79.67, 79.34, 79.01. MS ESI: (m/z) 270.4.