5-(2,6-Difluoro­phen­yl)-1,3,4-thia­diazol-2-amine

Abstract

The title compound, C₈H₅F₂N₃S, was synthesized by the reaction of 2,6-difluoro­benzoic acid and thio­semicarbazide. The dihedral angle between the thia­diazole and phenyl ring is 35.19 (14)°. In the crystal structure, inter­molecular N—H⋯N hydrogen bonds form chains along the b and c axes.

Related literature

For the biological activity of 1,3,4-thia­diazole derivatives, see: Nakagawa et al. (1996 ▶); Wang et al. (1999 ▶). For bond-length data see: Allen et al. (1987 ▶).

Experimental

Crystal data

• C₈H₅F₂N₃S

• M _r = 213.21

• Monoclinic,

• a = 9.0920 (18) Å

• b = 8.7400 (17) Å

• c = 10.936 (2) Å

• β = 95.85 (3)°

• V = 864.5 (3) ų

• Z = 4

• Mo Kα radiation

• μ = 0.37 mm⁻¹

• T = 293 K

• 0.20 × 0.10 × 0.10 mm

Data collection

• Enraf–Nonius CAD-4 diffractometer

• Absorption correction: ψ scan (North et al., 1968 ▶) T _min = 0.931, T _max = 0.964

• 1670 measured reflections

• 1568 independent reflections

• 1189 reflections with I > 2σ(I)

• R _int = 0.018

• 3 standard reflections every 200 reflections intensity decay: 1%

Refinement

• R[F ² > 2σ(F ²)] = 0.042

• wR(F ²) = 0.109

• S = 1.01

• 1568 reflections

• 127 parameters

• H-atom parameters constrained

• Δρ_max = 0.26 e Å⁻³

• Δρ_min = −0.28 e Å⁻³

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1989 ▶); cell refinement: CAD-4 EXPRESS; data reduction: XCAD4 (Harms & Wocadlo, 1995 ▶); 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: SHELXL97.

Supplementary Material

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—H3A⋯N2i	0.86	2.17	3.017 (4)	166
N3—H3B⋯N1ii	0.86	2.30	3.088 (3)	152

Symmetry codes: (i) ; (ii) .

supplementary crystallographic information

Comment

1,3,4-Thiadiazole derivatives represent a class of biologically important compounds, which often exhibit insecticidal, fungicidal and other biological activities (Nakagawa et al., 1996; Wang et al., 1999). We report here the crystal structure of the title compound, (I).

The molecular structure of (I) is shown in Fig.1, in which the bond lengths and angles are generally within normal ranges (Allen et al., 1987). The dihedral angle between the thiadiazole and phenyl ring is 35.19 (14)°. In the crystal structure, intermolecular N—H···N hydrogen bonds (Fig. 2) form chains along the b and c axes. There are also intermolecular N-H···S contacts between the molecules, which may further stabilize the structure.

Experimental

2,6-difluorobenzoic acid (2 mmol) and thiosemicarbazide (5 mmol) were mixed in a 25 ml flask, and kept in the oil bath at 90°C for 6 h. After cooling, the crude product (I) precipitated and was filtrated. Pure compound (I) was obtained by crystallization from ethanol (20 ml). Crystals of (I) suitable for X-ray diffraction were obtained by slow evaporation of an acetone solution.

Refinement

All H atoms bonded to the C atoms were placed geometrically at distances of 0.93–0.97 Å and included in the refinement in riding motion approximation with U_iso(H) = 1.2 or 1.5U_eq of the carrier atom.

Figures

Fig. 1.

A view of the molecular structure of (I). Displacement ellipsoids are drawn at the 50% probability level.

Fig. 2.

Partial packing view showing the hydrogen-bonded network. Dashed lines indicate intermolecular N—H···N hydrogen bonds and intermolecular N-H···S contacts between the molecules.

Crystal data

C8H5F2N3S	Dx = 1.638 Mg m−3
Mr = 213.21	Melting point: 533 K
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 9.0920 (18) Å	Cell parameters from 25 reflections
b = 8.7400 (17) Å	θ = 10–13°
c = 10.936 (2) Å	µ = 0.37 mm−1
β = 95.85 (3)°	T = 293 K
V = 864.5 (3) Å3	Block, colorless
Z = 4	0.20 × 0.10 × 0.10 mm
F(000) = 432

Data collection

Enraf–Nonius CAD-4 diffractometer	1189 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.018
graphite	θmax = 25.3°, θmin = 2.3°
ω/2θ scans	h = 0→10
Absorption correction: ψ scan (North et al., 1968)	k = 0→10
Tmin = 0.931, Tmax = 0.964	l = −13→13
1670 measured reflections	3 standard reflections every 200 reflections
1568 independent reflections	intensity decay: 1%

Refinement

Refinement on F2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.042	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.109	H-atom parameters constrained
S = 1.01	w = 1/[σ2(Fo2) + (0.060P)2 + 0.150P] where P = (Fo2 + 2Fc2)/3
1568 reflections	(Δ/σ)max < 0.001
127 parameters	Δρmax = 0.26 e Å−3
0 restraints	Δρmin = −0.28 e Å−3

Special details

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
S	0.68075 (8)	0.14488 (8)	0.16016 (6)	0.0423 (2)
F1	0.8904 (2)	0.0561 (2)	−0.18276 (16)	0.0637 (5)
N1	0.6608 (3)	0.1922 (3)	−0.07123 (19)	0.0475 (6)
C1	0.8942 (4)	−0.3350 (4)	−0.0851 (3)	0.0606 (9)
H1B	0.9319	−0.4285	−0.1078	0.073*
F2	0.6767 (2)	−0.1812 (2)	0.14183 (15)	0.0616 (5)
N2	0.6037 (3)	0.3224 (3)	−0.02139 (19)	0.0495 (6)
C2	0.9208 (3)	−0.2061 (4)	−0.1510 (3)	0.0531 (8)
H2B	0.9784	−0.2110	−0.2165	0.064*
N3	0.5574 (3)	0.4251 (3)	0.1678 (2)	0.0521 (7)
H3A	0.5209	0.5074	0.1338	0.062*
H3B	0.5620	0.4143	0.2462	0.062*
C3	0.8608 (3)	−0.0705 (3)	−0.1185 (2)	0.0442 (7)
C4	0.7736 (3)	−0.0549 (3)	−0.0209 (2)	0.0362 (6)
C5	0.7556 (3)	−0.1889 (3)	0.0433 (3)	0.0446 (7)
C6	0.8123 (4)	−0.3281 (3)	0.0144 (3)	0.0571 (8)
H6A	0.7961	−0.4149	0.0603	0.069*
C7	0.7062 (3)	0.0912 (3)	0.0101 (2)	0.0357 (6)
C8	0.6070 (3)	0.3142 (3)	0.0986 (2)	0.0376 (6)

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
S	0.0628 (5)	0.0382 (4)	0.0272 (3)	0.0092 (3)	0.0101 (3)	0.0052 (3)
F1	0.0799 (13)	0.0567 (11)	0.0601 (11)	0.0030 (10)	0.0351 (10)	0.0104 (9)
N1	0.0737 (17)	0.0411 (12)	0.0278 (11)	0.0138 (12)	0.0064 (11)	−0.0010 (9)
C1	0.069 (2)	0.0476 (18)	0.065 (2)	0.0180 (16)	0.0049 (17)	−0.0093 (16)
F2	0.0825 (13)	0.0493 (10)	0.0580 (11)	0.0069 (9)	0.0309 (10)	0.0111 (8)
N2	0.0803 (18)	0.0405 (13)	0.0280 (11)	0.0176 (12)	0.0069 (11)	0.0017 (10)
C2	0.0503 (18)	0.063 (2)	0.0471 (17)	0.0128 (16)	0.0116 (14)	−0.0065 (15)
N3	0.0824 (19)	0.0448 (13)	0.0304 (12)	0.0185 (13)	0.0128 (12)	0.0008 (10)
C3	0.0479 (16)	0.0468 (16)	0.0384 (14)	0.0020 (13)	0.0071 (13)	0.0000 (12)
C4	0.0389 (15)	0.0363 (14)	0.0333 (13)	0.0015 (11)	0.0035 (11)	−0.0016 (11)
C5	0.0468 (16)	0.0446 (15)	0.0430 (15)	0.0022 (13)	0.0077 (13)	0.0015 (13)
C6	0.069 (2)	0.0377 (16)	0.065 (2)	0.0041 (15)	0.0080 (17)	0.0039 (14)
C7	0.0432 (15)	0.0362 (13)	0.0279 (12)	0.0014 (12)	0.0051 (11)	0.0011 (11)
C8	0.0481 (16)	0.0348 (14)	0.0298 (13)	0.0042 (12)	0.0042 (11)	0.0032 (10)

Geometric parameters (Å, °)

S—C8	1.733 (3)	C2—C3	1.367 (4)
S—C7	1.745 (2)	C2—H2B	0.9300
F1—C3	1.352 (3)	N3—C8	1.336 (3)
N1—C7	1.291 (3)	N3—H3A	0.8600
N1—N2	1.385 (3)	N3—H3B	0.8600
C1—C2	1.372 (4)	C3—C4	1.400 (4)
C1—C6	1.382 (4)	C4—C5	1.384 (4)
C1—H1B	0.9300	C4—C7	1.471 (3)
F2—C5	1.356 (3)	C5—C6	1.370 (4)
N2—C8	1.311 (3)	C6—H6A	0.9300
C8—S—C7	86.98 (12)	C5—C4—C3	114.2 (2)
C7—N1—N2	113.4 (2)	C5—C4—C7	123.0 (2)
C2—C1—C6	121.1 (3)	C3—C4—C7	122.8 (2)
C2—C1—H1B	119.5	F2—C5—C6	118.0 (2)
C6—C1—H1B	119.5	F2—C5—C4	117.4 (2)
C8—N2—N1	112.2 (2)	C6—C5—C4	124.6 (3)
C3—C2—C1	118.6 (3)	C5—C6—C1	117.8 (3)
C3—C2—H2B	120.7	C5—C6—H6A	121.1
C1—C2—H2B	120.7	C1—C6—H6A	121.1
C8—N3—H3A	120.0	N1—C7—C4	123.1 (2)
C8—N3—H3B	120.0	N1—C7—S	113.60 (19)
H3A—N3—H3B	120.0	C4—C7—S	123.26 (18)
F1—C3—C2	117.9 (2)	N2—C8—N3	123.6 (2)
F1—C3—C4	118.4 (2)	N2—C8—S	113.82 (19)
C2—C3—C4	123.7 (3)	N3—C8—S	122.63 (19)
C7—N1—N2—C8	−0.5 (4)	C2—C1—C6—C5	1.5 (5)
C6—C1—C2—C3	−1.9 (5)	N2—N1—C7—C4	−178.8 (2)
C1—C2—C3—F1	178.7 (3)	N2—N1—C7—S	0.9 (3)
C1—C2—C3—C4	0.2 (5)	C5—C4—C7—N1	−146.4 (3)
F1—C3—C4—C5	−176.8 (2)	C3—C4—C7—N1	33.2 (4)
C2—C3—C4—C5	1.6 (4)	C5—C4—C7—S	33.9 (4)
F1—C3—C4—C7	3.6 (4)	C3—C4—C7—S	−146.5 (2)
C2—C3—C4—C7	−178.0 (3)	C8—S—C7—N1	−0.7 (2)
C3—C4—C5—F2	177.7 (2)	C8—S—C7—C4	178.9 (2)
C7—C4—C5—F2	−2.7 (4)	N1—N2—C8—N3	−179.6 (3)
C3—C4—C5—C6	−2.1 (4)	N1—N2—C8—S	−0.1 (3)
C7—C4—C5—C6	177.5 (3)	C7—S—C8—N2	0.4 (2)
F2—C5—C6—C1	−179.2 (3)	C7—S—C8—N3	−180.0 (3)
C4—C5—C6—C1	0.6 (5)

Hydrogen-bond geometry (Å, °)

D—H···A	D—H	H···A	D···A	D—H···A
N3—H3A···N2i	0.86	2.17	3.017 (4)	166
N3—H3B···N1ii	0.86	2.30	3.088 (3)	152

Symmetry codes: (i) −x+1, −y+1, −z; (ii) x, −y+1/2, z+1/2.