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Acta Cryst. (2009). E65, o2166-o2167    [ doi:10.1107/S1600536809031675 ]

N,N-Bis(2,6-difluorobenzyl)-1,3,4-thiadiazol-2-amine

H.-K. Fun, W.-C. Liew, B. Chandrakantha and A. M. Isloor

Abstract top

In the title compound, C16H11F4N3S, the dihedral angles between the thiadiazole ring and the difluorobenzyl rings are 81.95 (7) and 81.96 (7)°, whereas the dihedral angle between the difluorobenzyl rings is 11.41 (7)°. In the crystal structure, C-H...N and C-H...F interactions link the molecules into two-dimensional arrays parallel to the bc plane.

Comment top

Heterocycles bearing 1,3,4-thiadiazole moieties represent an interesting class of compounds possessing a wide spectrum of biological activity (Swamy et al., 2006) such as anti-inflammatory, anti-viral and anti-microbial properties (Amir & Shikha, 2004). Recently, 1,3,4-thiadiazoles have attracted particular attention due to their analgesic, ulcerogenic and lipidperoxidation activities (Holla et al., 2002). In particular, the derivatives of variously substituted 1,3,4-thiadiazoles are also known to exhibit anti-depressant and anxiolitic agents (Ibrahim, 2009). Herein, the crystal structure of the title compound (I) is reported.

In (I), Fig. 1, the bond lengths and angles are comparable to related structures (Wang et al., 2009a & b; Yin et al., 2008). The dihedral angles between the thiadiazole ring (C1—C2/S1/N1—N2) and the difluorobenzyl rings [(C4—C9) and (C11—C16)] are 81.95 (7)° and 81.86 (7)°, respectively whereas the dihedral angle between the difluorobenzyl rings is 11.41 (7)°. These data indicate that all the three rings are twisted from each other.

The crystal packing (Fig. 2) is consolidated by C—H···N and C—H···F interactions (Table 1) that link molecules into two-dimensional arrays parallel to the bc plane.

Related literature top

For the synthesis of pharmaceutically condensed heterocyclic thiadiazole derivatives as antimicrobials, see: Swamy et al. (2006). For the synthesis and anti-inflammatory, analgesic, ulcerogenic and lipid peroxidation activity of some new acetic acid derivatives, see: Amir & Shikha (2004). For new bis-aminomercaptotriazoles and bis-triazolothiadiazoles as possible anticancer agents, see: Holla et al. (2002). For the synthesis and biological evaluation of thiadiazole derivatives as a novel class of potential anti-tumor agents, see: Ibrahim (2009). For related structures, see: Wang et al. (2009a,b); Yin et al. (2008). For the stability of the temperature controller used in the data collection, see: Cosier & Glazer (1986).

Experimental top

Anhydrous potassium carbonate (5.4 g, 0.0395 mol) was added to a solution of 1,3,4-thiadiazole-2-amine (2 g, 0.0197 mol) in dry acetonitrile (25 ml). The reaction mixture was stirred for 15 min. 2,6-Difluorobenzyl bromide (8.18 g, 0.0395 mol) was added drop-wise to the mixture. After addition, the reaction mixture was stirred at room temperature for 18 h, filtered, and the filtrate was concentrated. The crude product was purified by column chromatography using 60–120 silica gel. The fraction eluted with 10% ethyl acetate in hexane was concentrated to produce (I) as a pale-yellow crystalline solid. Yield 5.0 g, 71.63%. m.p. 421–423 K.

Refinement top

C-bound H atoms were positioned geometrically [C—H = 0.93 and 0.97 Å] and refined using a riding model with Uiso(H) = 1.2Ueq(C).

Computing details top

Data collection: APEX2 (Bruker, 2005); cell refinement: SAINT (Bruker, 2005); data reduction: SAINT (Bruker, 2005); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).

Figures top
[Figure 1] Fig. 1. The molecular structure of (I), showing 50% probability displacement ellipsoids and the atom numbering scheme.
[Figure 2] Fig. 2. Crystal packing viewed along the b-axis. C-H···N and C-H···F interactions are shown as dashed lines.
N,N-Bis(2,6-difluorobenzyl)-1,3,4-thiadiazol-2-amine top
Crystal data top
C16H11F4N3SF(000) = 720
Mr = 353.34Dx = 1.571 Mg m−3
Orthorhombic, Pca21Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2c -2acCell parameters from 9387 reflections
a = 32.6678 (6) Åθ = 2.9–33.7°
b = 5.8515 (1) ŵ = 0.26 mm−1
c = 7.8140 (2) ÅT = 100 K
V = 1493.69 (5) Å3Block, pale-yellow
Z = 40.46 × 0.33 × 0.14 mm
Data collection top
Bruker SMART APEXII CCD area-detector
diffractometer		4796 independent reflections
Radiation source: fine-focus sealed tube4299 reflections with I > 2σ(I)
graphiteRint = 0.027
φ and ω scansθmax = 32.5°, θmin = 2.5°
Absorption correction: multi-scan
(SADABS; Bruker, 2005)		h = −48→46
Tmin = 0.887, Tmax = 0.965k = −8→8
17980 measured reflectionsl = −11→11
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.033H-atom parameters constrained
wR(F2) = 0.076 w = 1/[σ2(Fo2) + (0.0345P)2 + 0.2893P]
where P = (Fo2 + 2Fc2)/3
S = 1.02(Δ/σ)max = 0.001
4796 reflectionsΔρmax = 0.23 e Å−3
218 parametersΔρmin = −0.26 e Å−3
1 restraintAbsolute structure: Flack (1983), 1935 Friedel pairs
Primary atom site location: structure-invariant direct methodsFlack parameter: 0.20 (5)
Crystal data top
C16H11F4N3SV = 1493.69 (5) Å3
Mr = 353.34Z = 4
Orthorhombic, Pca21Mo Kα radiation
a = 32.6678 (6) ŵ = 0.26 mm−1
b = 5.8515 (1) ÅT = 100 K
c = 7.8140 (2) Å0.46 × 0.33 × 0.14 mm
Data collection top
Bruker SMART APEXII CCD area-detector
diffractometer		4796 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2005)		4299 reflections with I > 2σ(I)
Tmin = 0.887, Tmax = 0.965Rint = 0.027
17980 measured reflectionsθmax = 32.5°
Refinement top
R[F2 > 2σ(F2)] = 0.033H-atom parameters constrained
wR(F2) = 0.076Δρmax = 0.23 e Å−3
S = 1.02Δρmin = −0.26 e Å−3
4796 reflectionsAbsolute structure: Flack (1983), 1935 Friedel pairs
218 parametersFlack parameter: 0.20 (5)
1 restraint
Special details top

Experimental. The crystal was placed in the cold stream of an Oxford Cyrosystems Cobra open-flow nitrogen cryostat (Cosier & Glazer, 1986) operating at 100.0 (1) K.

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 (Å2) top
xyzUiso*/Ueq
S10.794704 (10)0.52906 (6)−0.01577 (5)0.02346 (8)
F10.79830 (2)0.37874 (17)0.48808 (16)0.0338 (2)
F20.94005 (2)0.27091 (16)0.53340 (11)0.0261 (2)
F30.92412 (3)−0.07230 (15)0.24104 (14)0.0264 (2)
F40.91204 (3)0.60294 (17)−0.07755 (14)0.0338 (2)
N10.78098 (4)0.8994 (2)0.14916 (18)0.0236 (3)
N20.81456 (4)0.8012 (2)0.22916 (17)0.0209 (2)
N30.85771 (4)0.4805 (2)0.21110 (16)0.0190 (2)
C10.76794 (4)0.7789 (3)0.0214 (2)0.0249 (3)
H1A0.74580.8235−0.04550.030*
C20.82545 (4)0.6085 (2)0.15657 (18)0.0160 (2)
C30.87577 (4)0.5273 (2)0.3784 (2)0.0187 (3)
H3A0.86370.66550.42490.022*
H3B0.90490.55370.36470.022*
C40.86929 (4)0.3330 (2)0.50333 (18)0.0162 (2)
C50.83046 (4)0.2629 (3)0.5541 (2)0.0213 (3)
C60.82293 (5)0.0864 (3)0.6657 (2)0.0242 (3)
H6A0.79630.04680.69550.029*
C70.85629 (5)−0.0312 (3)0.7328 (2)0.0238 (3)
H7A0.8520−0.15230.80780.029*
C80.89596 (5)0.0308 (3)0.68863 (19)0.0220 (3)
H8A0.9184−0.04660.73340.026*
C90.90109 (4)0.2105 (2)0.57631 (19)0.0181 (3)
C100.87024 (4)0.2743 (2)0.1207 (2)0.0194 (3)
H10A0.85570.26560.01260.023*
H10B0.86270.14170.18820.023*
C110.91598 (4)0.2685 (2)0.08670 (19)0.0175 (3)
C120.94120 (4)0.0961 (2)0.14585 (18)0.0184 (3)
C130.98273 (5)0.0831 (3)0.1130 (2)0.0234 (3)
H13A0.9984−0.03740.15480.028*
C141.00032 (4)0.2553 (3)0.0158 (2)0.0260 (3)
H14A1.02820.2512−0.00720.031*
C150.97688 (5)0.4331 (3)−0.0475 (2)0.0272 (3)
H15A0.98860.5489−0.11250.033*
C160.93555 (4)0.4336 (2)−0.0113 (2)0.0218 (3)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
S10.01673 (15)0.03179 (18)0.02187 (15)0.00300 (13)−0.00547 (14)−0.00224 (18)
F10.0139 (4)0.0423 (5)0.0451 (5)0.0051 (4)−0.0022 (4)0.0137 (6)
F20.0124 (4)0.0360 (5)0.0298 (5)0.0007 (3)−0.0012 (3)0.0101 (4)
F30.0237 (4)0.0208 (4)0.0345 (5)0.0013 (3)0.0037 (4)0.0108 (4)
F40.0341 (5)0.0282 (5)0.0390 (5)0.0040 (4)−0.0034 (4)0.0175 (4)
N10.0206 (6)0.0248 (6)0.0253 (6)0.0062 (5)−0.0010 (5)0.0065 (5)
N20.0187 (6)0.0213 (6)0.0226 (6)0.0044 (4)−0.0020 (5)0.0032 (5)
N30.0181 (5)0.0192 (5)0.0196 (5)0.0039 (4)−0.0049 (4)−0.0013 (5)
C10.0165 (6)0.0339 (8)0.0243 (7)0.0059 (6)−0.0018 (5)0.0044 (6)
C20.0127 (6)0.0192 (6)0.0161 (5)−0.0015 (5)−0.0012 (4)0.0041 (5)
C30.0192 (6)0.0172 (6)0.0198 (6)−0.0007 (5)−0.0054 (5)0.0006 (5)
C40.0132 (5)0.0177 (6)0.0177 (6)0.0003 (4)−0.0022 (5)0.0000 (5)
C50.0150 (6)0.0230 (7)0.0258 (7)0.0015 (5)−0.0015 (5)0.0003 (6)
C60.0199 (7)0.0277 (8)0.0250 (7)−0.0054 (6)0.0019 (5)0.0003 (6)
C70.0296 (8)0.0218 (7)0.0200 (7)−0.0022 (6)0.0024 (6)0.0032 (6)
C80.0220 (7)0.0233 (7)0.0206 (7)0.0039 (6)−0.0031 (5)0.0030 (6)
C90.0141 (6)0.0208 (6)0.0193 (6)−0.0005 (5)−0.0004 (5)0.0001 (5)
C100.0167 (6)0.0180 (6)0.0235 (7)0.0011 (5)−0.0027 (5)−0.0023 (6)
C110.0167 (6)0.0176 (6)0.0181 (6)0.0001 (5)−0.0012 (5)0.0001 (5)
C120.0203 (6)0.0164 (6)0.0185 (6)−0.0009 (5)0.0014 (5)0.0005 (5)
C130.0201 (7)0.0243 (7)0.0259 (7)0.0049 (5)0.0009 (5)−0.0005 (6)
C140.0184 (6)0.0345 (8)0.0252 (8)−0.0026 (6)0.0044 (5)−0.0024 (7)
C150.0278 (8)0.0299 (8)0.0238 (8)−0.0075 (6)0.0042 (6)0.0053 (6)
C160.0252 (7)0.0191 (6)0.0211 (6)0.0009 (5)−0.0027 (6)0.0058 (7)
Geometric parameters (Å, °) top
S1—C11.7278 (16)C6—C71.392 (2)
S1—C21.7431 (14)C6—H6A0.9300
F1—C51.3527 (16)C7—C81.389 (2)
F2—C91.3630 (15)C7—H7A0.9300
F3—C121.3548 (17)C8—C91.380 (2)
F4—C161.3566 (16)C8—H8A0.9300
N1—C11.295 (2)C10—C111.5179 (19)
N1—N21.3872 (16)C10—H10A0.9700
N2—C21.3114 (19)C10—H10B0.9700
N3—C21.3613 (17)C11—C121.3824 (19)
N3—C101.4570 (18)C11—C161.388 (2)
N3—C31.4598 (19)C12—C131.383 (2)
C1—H1A0.9300C13—C141.387 (2)
C3—C41.514 (2)C13—H13A0.9300
C3—H3A0.9700C14—C151.383 (2)
C3—H3B0.9700C14—H14A0.9300
C4—C91.3848 (18)C15—C161.380 (2)
C4—C51.3906 (19)C15—H15A0.9300
C5—C61.374 (2)
C1—S1—C286.35 (7)C9—C8—C7118.05 (14)
C1—N1—N2112.47 (13)C9—C8—H8A121.0
C2—N2—N1112.07 (13)C7—C8—H8A121.0
C2—N3—C10121.42 (12)F2—C9—C8117.87 (12)
C2—N3—C3119.33 (12)F2—C9—C4117.72 (12)
C10—N3—C3118.42 (11)C8—C9—C4124.41 (13)
N1—C1—S1115.07 (11)N3—C10—C11112.32 (11)
N1—C1—H1A122.5N3—C10—H10A109.1
S1—C1—H1A122.5C11—C10—H10A109.1
N2—C2—N3123.20 (13)N3—C10—H10B109.1
N2—C2—S1114.03 (10)C11—C10—H10B109.1
N3—C2—S1122.77 (11)H10A—C10—H10B107.9
N3—C3—C4112.33 (11)C12—C11—C16114.68 (12)
N3—C3—H3A109.1C12—C11—C10122.98 (12)
C4—C3—H3A109.1C16—C11—C10122.31 (13)
N3—C3—H3B109.1F3—C12—C11117.97 (12)
C4—C3—H3B109.1F3—C12—C13117.77 (13)
H3A—C3—H3B107.9C11—C12—C13124.25 (13)
C9—C4—C5114.46 (13)C12—C13—C14117.94 (14)
C9—C4—C3123.33 (11)C12—C13—H13A121.0
C5—C4—C3122.21 (12)C14—C13—H13A121.0
F1—C5—C6118.65 (13)C15—C14—C13120.85 (14)
F1—C5—C4116.87 (13)C15—C14—H14A119.6
C6—C5—C4124.48 (14)C13—C14—H14A119.6
C5—C6—C7118.08 (14)C16—C15—C14118.03 (14)
C5—C6—H6A121.0C16—C15—H15A121.0
C7—C6—H6A121.0C14—C15—H15A121.0
C8—C7—C6120.51 (14)F4—C16—C15118.49 (13)
C8—C7—H7A119.7F4—C16—C11117.26 (12)
C6—C7—H7A119.7C15—C16—C11124.24 (13)
C1—N1—N2—C20.11 (18)C7—C8—C9—C4−0.5 (2)
N2—N1—C1—S10.64 (17)C5—C4—C9—F2−179.53 (12)
C2—S1—C1—N1−0.89 (12)C3—C4—C9—F20.5 (2)
N1—N2—C2—N3179.58 (13)C5—C4—C9—C80.9 (2)
N1—N2—C2—S1−0.80 (15)C3—C4—C9—C8−179.07 (14)
C10—N3—C2—N2−176.38 (13)C2—N3—C10—C11131.34 (14)
C3—N3—C2—N214.2 (2)C3—N3—C10—C11−59.13 (17)
C10—N3—C2—S14.04 (19)N3—C10—C11—C12121.31 (15)
C3—N3—C2—S1−165.40 (10)N3—C10—C11—C16−60.72 (19)
C1—S1—C2—N20.94 (11)C16—C11—C12—F3−179.37 (13)
C1—S1—C2—N3−179.44 (13)C10—C11—C12—F3−1.3 (2)
C2—N3—C3—C4113.44 (14)C16—C11—C12—C130.1 (2)
C10—N3—C3—C4−56.32 (16)C10—C11—C12—C13178.17 (14)
N3—C3—C4—C9118.26 (15)F3—C12—C13—C14−179.93 (14)
N3—C3—C4—C5−61.69 (18)C11—C12—C13—C140.6 (2)
C9—C4—C5—F1179.22 (13)C12—C13—C14—C15−0.6 (2)
C3—C4—C5—F1−0.8 (2)C13—C14—C15—C16−0.1 (2)
C9—C4—C5—C6−0.6 (2)C14—C15—C16—F4−177.79 (14)
C3—C4—C5—C6179.38 (14)C14—C15—C16—C110.9 (2)
F1—C5—C6—C7−179.92 (14)C12—C11—C16—F4177.85 (13)
C4—C5—C6—C7−0.1 (2)C10—C11—C16—F4−0.3 (2)
C5—C6—C7—C80.6 (2)C12—C11—C16—C15−0.9 (2)
C6—C7—C8—C9−0.3 (2)C10—C11—C16—C15−178.99 (15)
C7—C8—C9—F2179.95 (13)
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
C1—H1A···N1i0.932.583.392 (2)146
C3—H3A···N20.972.362.8155 (18)108
C3—H3B···F20.972.412.8508 (15)107
C3—H3B···F3ii0.972.473.0226 (16)116
C8—H8A···F4iii0.932.543.144 (2)123
C10—H10A···S10.972.533.0738 (14)115
C10—H10B···F30.972.402.8453 (16)107
C10—H10B···N2iv0.972.563.4191 (17)148
Symmetry codes: (i) −x+3/2, y, z−1/2; (ii) x, y+1, z; (iii) x, y−1, z+1; (iv) x, y−1, z.
Table 1
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
C1—H1A···N1i0.932.583.392 (2)146
C3—H3B···F3ii0.972.473.0226 (16)116
C8—H8A···F4iii0.932.543.144 (2)123
C10—H10B···N2iv0.972.563.4191 (17)148
Symmetry codes: (i) −x+3/2, y, z−1/2; (ii) x, y+1, z; (iii) x, y−1, z+1; (iv) x, y−1, z.
Acknowledgements top

HKF and WCL thank Universiti Sains Malaysia (USM) for a Research University Golden Goose Grant (No. 1001/PFIZIK/811012). WCL thanks USM for a USM Fellowship. AMI is grateful to the Director, NITK Surathkal, India, for providing research facilities.

references
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