5-Amino-1,3,4-thia­diazol-2(3H)-one

Sung Kwon Kang; Nam Sook Cho; Siyoung Jang

doi:10.1107/S1600536812012433

. 2012 Mar 28;68(Pt 4):o1198. doi: 10.1107/S1600536812012433

5-Amino-1,3,4-thiadiazol-2(3H)-one

Sung Kwon Kang ^a,^*, Nam Sook Cho ^a, Siyoung Jang ^a

PMCID: PMC3344135 PMID: 22606138

Abstract

The asymmetric unit of the title compound, C₂H₃N₃OS, contains three independent molecules which are essentially planar, with r.m.s. deviations of 0.011 (2)–0.027 (2) Å from the mean plane defined by the seven non-H atoms. In the crystal, N—H⋯N and N—H⋯O hydrogen bonds link the molecules into a sheet parallel to the (111) plane.

Related literature

For the structures and reactivity of thiadiazole derivatives, see: Parkanyi et al. (1989 ▶); Cho, Cho et al. (1996 ▶); Cho, Ra et al. (1996 ▶). For the biological activity of thiadiazole derivatives, see: Castro et al. (2008 ▶); Ra, Cho & Cho (1998 ▶); Ra, Cho, Moon & Kang (1998 ▶).

Experimental

Crystal data

C₂H₃N₃OS
M _r = 117.13
Triclinic,
a = 7.2860 (2) Å
b = 10.2982 (3) Å
c = 10.7727 (3) Å
α = 63.721 (3)°
β = 73.122 (2)°
γ = 76.737 (2)°
V = 688.74 (3) Å³
Z = 6
Mo Kα radiation
μ = 0.57 mm⁻¹
T = 296 K
0.15 × 0.1 × 0.05 mm

Data collection

Bruker SMART CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2002 ▶) T _min = 0.93, T _max = 0.97
23857 measured reflections
3433 independent reflections
2526 reflections with I > 2σ(I)
R _int = 0.055

Refinement

R[F ² > 2σ(F ²)] = 0.031
wR(F ²) = 0.080
S = 0.94
3433 reflections
226 parameters
All H-atom parameters refined
Δρ_max = 0.30 e Å⁻³
Δρ_min = −0.26 e Å⁻³

Data collection: SMART (Bruker, 2002 ▶); cell refinement: SAINT (Bruker, 2002 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 (Farrugia, 1997 ▶); software used to prepare material for publication: WinGX (Farrugia, 1999 ▶).

Supplementary Material

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S1600536812012433/is5096sup1.cif

e-68-o1198-sup1.cif^{(19.4KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812012433/is5096Isup2.hkl

e-68-o1198-Isup2.hkl^{(164.9KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536812012433/is5096Isup3.cml

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
N3—H3⋯N18	0.854 (19)	2.004 (19)	2.8516 (19)	171.9 (18)
N7—H7A⋯O20ⁱ	0.87 (2)	2.07 (2)	2.907 (2)	160 (2)
N10—H10⋯N4	0.98 (2)	1.88 (2)	2.8558 (19)	175.7 (18)
N14—H14A⋯O6ⁱⁱ	0.83 (2)	2.10 (2)	2.897 (2)	162 (2)
N17—H17⋯N11	0.88 (2)	1.97 (2)	2.8424 (18)	179 (4)
N21—H21A⋯O13ⁱⁱⁱ	0.80 (3)	2.10 (3)	2.878 (2)	163 (2)

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

supplementary crystallographic information

Comment

5-Amino-2H-1,2,4-thiadiazolin-3-one heterocycle is an analog of cytosine (Parkanyi et al., 1989). Derivatives of 5-amino-2H-1,2,4-thiadiazolin-3-one have recently attracted attention on the antibacterial activity, potential carcinogenicity, and kinase inhibitor activity (Castro et al., 2008; Cho, Ra et al., 1996; Ra, Cho, Moon & Kang, 1998). 5-Amino-3H-1,3,4-thiadiazolin-2-one is an isomer of 5-amino-2H-1,2,4-thiadiazolin-3-one, which has become an attractive moiety due to potential biological activities (Cho, Cho, Ra, Moon et al., 1996; Ra, Cho & Cho 1998).

In (I), three independent but similar molecules, which are linked by the intermolecular N—H···N hydrogen bonds (Fig. 1), comprise the asymmetric unit. The 1,3,4-thiadiazolin-2-one units are almost planar with r.m.s. deviations of 0.011 (2)–0.027 (2) Å from the corresponding least-squares plane defined by the seven constituent atoms. The bond distance of N4—C5 [1.291 (2) Å; N11—C12, 1.287 (2) Å; N18—C19, 1.282 (2) Å] is shorter than that of C2—N3 [1.333 (2) Å; C9—N10, 1.336 (2) Å; C16—N17, 1.327 Å], which is consistent with double bond character. The crystal structure is stabilized by the intermolecular N—H···N and N—H···O hydrogen bonds, which link the molecules into a two-dimensional sheet parallel to the (111) plane (Table 1 and Fig. 2).

Experimental

Synthesis of 5-amino-2-ethoxy-1,3,4-thiadiazole: Ethyl thiocarbazate (4.8 g, 0.04 mol) was dissolved in 24 ml of 2 N NaOH at 10 °C. Cyanogen bromide (4.2 g, 0.04 mol) dissolved in 20 ml of ethanol was added to the above solution keeping the temperature below 10 °C during 45 minutes. The solid product (4.1 g, 71%) was collected by filtration. To obtain the analytical sample the product was recrystallized from ethanol. m.p. 200–202 °C; IR (KBr, cm^-1) 3300 (NH), 3150 (NH), 3000 (CH), 2950 (CH), 1620 (C=O), 1580 (C=N); ¹H NMR (DMSO-d₆, p.p.m.) 6.65 (2H, b, NH₂), 4.25 (2H, q, CH₂), 1.29 (3H, t, CH₃); ¹³C NMR (DMSO-d₆, p.p.m.) 164.85 (C=N), 162.18 (C—O), 67.48 (CH₂), 14.35 (CH₃); Anal. Calcd. For C₄H₇N₃OS: C 33.09, H 4.86, N 28.94. Found: C 33.71, H 4.94, N 28.50.

Synthesis of title compound: 5-Amino-2-ethoxy-1,3,4-thiadiazole (5 g, 34.5 mmol) was dissolved in 50 ml of dioxane and 3.5 ml of c-HCl was added. The reaction mixture was refluxed for 4.5 h. The solvent was distilled off under reduced pressure. The residue product was washed with ether (3.7 g, 92.5%). To obtain the analytical sample the product was recrystallized from water. Recrystallization from DMSO afforded the colorless crystals suitable for X-ray diffraction. m.p. 176–178 °C; IR (KBr, cm^-1) 3450 (NH), 3150 (NH), 3100, 3000, 2900 (CH), 1700 (C=O), 1610, 1500 (C=N); ¹H NMR (DMSO-d₆, p.p.m.) 11.3 (1H, b, NH), 6.4 (2H, b, NH₂; ¹³C NMR (DMSO-d₆, p.p.m.) 169.4 (C=N), 153.0 (C=O); Anal. Calcd. For C₂H₃N₃OS: C 20.51, H 2.58, N 35.88, S 27.37. Found: C 20.19, H 2.65, N 34.28, S 27.22.