organic compounds
5-Chloro-N-(4,5-dihydro-1H-imidazol-2-yl)-2,1,3-benzothiadiazol-4-amine (tizanidine)
aMaterials Chemistry Laboratory, Department of Chemistry, GC University, Lahore 54000, Pakistan, and bDepartment of Physics, Faculty of Sciences, Erciyes University, 38039 Kayseri, Turkey
*Correspondence e-mail: akkurt@erciyes.edu.tr, iukhan@gcu.edu.pk
There are two independent molecules (A and B) with similar conformations in the of the title compound, C9H8ClN5S. The benzothiadiazole ring systems of both molecules are essentially planar [maximum deviation = 0.021 (2) Å in molecule A and 0.022 (1) Å in molecule B] and make dihedral angles of 68.78 (9) and 54.39 (8)°, respectively, with the mean planes of their 4,5-dihydro-1H-imidazole rings. An intramolecular N—H⋯Cl hydrogen bond occurs in molecule B. In the crystal, both molecules form centrosymmetric dimers through π-stacking of their benzothiadiazole rings, with interplanar distances of 3.3174 (7) and 3.2943 (6) Å. These dimers are further linked via pairs of N—H⋯N hydrogen bonds with the dihydroimidazole rings as the hydrogen-bonding donors and one of the benzothiadiazole N atoms as the acceptors, generating R22(16) ring motifs. The A2 and B2 dimers in turn form additional N—H⋯N hydrogen bonds with the secondary amine as the H-atom donor and the dihydroimidazole N atom as the acceptor. These R22(8)-type interactions connect the A2 and B2 dimers with each other, forming infinite chains along [11].
Related literature
For the medicinal importance of tizanidine, see: Koch et al. (1989); Shellenberger et al. (1999); Tse et al. (1987). For hydrogen-bond motifs, see: Bernstein et al. (1995).
Experimental
Crystal data
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Data collection
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Refinement
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Data collection: APEX2 (Bruker, 2007); cell SAINT (Bruker, 2007); 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 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999) and PLATON (Spek, 2009).
Supporting information
10.1107/S1600536811008348/zl2351sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536811008348/zl2351Isup2.hkl
To 0.3 g of tizanidine in 10 ml methanol were added several drops of sodium hydroxide solution (3%) to adjust the pH to 8. The resulting solution was left for slow evaporation. Orange crystals were obtained after three days.
In the last cycles of the
24 reflections were eliminated due to being poorly measured in the vicinity of the beam stop. The H atoms of the NH groups of the molecules A and B were located in a difference map and refined with a distance restraint of N—H = 0.86 (3) Å. Their isotropic displacement parameters were set to be 1.2Ueq(N). The HN3A···N5B distance was restrained to be 2.00 (2) Å. The other H atoms were positioned geometrically with C—H = 0.93 and 0.97 Å, and allowed to ride on their parent atoms, with Uiso(H) = 1.2Ueq(C).Data collection: APEX2 (Bruker, 2007); cell
SAINT (Bruker, 2007); data reduction: SAINT (Bruker, 2007); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999) and PLATON (Spek, 2009).Fig. 1. View of the two crystallographically independent molecules, A and B, with the atom numbering scheme. Displacement ellipsoids for non-H atoms are drawn at the 50% probability level. | |
Fig. 2. An overlay of the two molecules A (black line) and B (red line). | |
Fig. 3. A view of the π-π stacking interactions and the hydrogen bonding of the title compound. The H atoms not involved in the hydrogen bonds forming the complete motif were omitted. (Symmetry codes: (e) 1-x, 1-y, 1-z; (f) 3-x, -y, 2-z). |
C9H8ClN5S | Z = 4 |
Mr = 253.72 | F(000) = 520 |
Triclinic, P1 | Dx = 1.593 Mg m−3 |
Hall symbol: -P 1 | Mo Kα radiation, λ = 0.71073 Å |
a = 7.6927 (3) Å | Cell parameters from 9959 reflections |
b = 10.8558 (4) Å | θ = 2.9–28.3° |
c = 12.9969 (5) Å | µ = 0.54 mm−1 |
α = 95.790 (1)° | T = 296 K |
β = 101.126 (1)° | Block, orange |
γ = 92.192 (1)° | 0.29 × 0.18 × 0.08 mm |
V = 1057.69 (7) Å3 |
Bruker APEXII CCD diffractometer | 4449 reflections with I > 2σ(I) |
Radiation source: sealed tube | Rint = 0.024 |
Graphite monochromator | θmax = 28.3°, θmin = 3.2° |
ϕ and ω scans | h = −10→10 |
17897 measured reflections | k = −14→14 |
5104 independent reflections | l = −17→17 |
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) = 0.120 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.03 | w = 1/[σ2(Fo2) + (0.0635P)2 + 0.4931P] where P = (Fo2 + 2Fc2)/3 |
5104 reflections | (Δ/σ)max = 0.001 |
302 parameters | Δρmax = 0.65 e Å−3 |
5 restraints | Δρmin = −0.43 e Å−3 |
C9H8ClN5S | γ = 92.192 (1)° |
Mr = 253.72 | V = 1057.69 (7) Å3 |
Triclinic, P1 | Z = 4 |
a = 7.6927 (3) Å | Mo Kα radiation |
b = 10.8558 (4) Å | µ = 0.54 mm−1 |
c = 12.9969 (5) Å | T = 296 K |
α = 95.790 (1)° | 0.29 × 0.18 × 0.08 mm |
β = 101.126 (1)° |
Bruker APEXII CCD diffractometer | 4449 reflections with I > 2σ(I) |
17897 measured reflections | Rint = 0.024 |
5104 independent reflections |
R[F2 > 2σ(F2)] = 0.042 | 5 restraints |
wR(F2) = 0.120 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.03 | Δρmax = 0.65 e Å−3 |
5104 reflections | Δρmin = −0.43 e Å−3 |
302 parameters |
Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles |
Refinement. Refinement on F2 for ALL reflections except those flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The observed criterion of F2 > σ(F2) is used only for calculating -R-factor-obs 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. |
x | y | z | Uiso*/Ueq | ||
Cl1A | 0.40681 (8) | 0.26166 (5) | 0.72358 (5) | 0.0597 (2) | |
S1A | 0.85136 (8) | 0.69598 (5) | 0.58255 (5) | 0.0609 (2) | |
N1A | 0.6430 (3) | 0.71482 (15) | 0.57232 (14) | 0.0518 (5) | |
N2A | 0.8692 (2) | 0.56543 (15) | 0.63157 (15) | 0.0504 (5) | |
N3A | 0.7911 (2) | 0.33724 (14) | 0.71346 (12) | 0.0441 (5) | |
N4A | 0.6996 (2) | 0.18129 (15) | 0.56630 (12) | 0.0426 (4) | |
N5A | 0.9113 (2) | 0.14570 (13) | 0.69909 (11) | 0.0393 (4) | |
C1A | 0.4819 (3) | 0.39656 (17) | 0.68103 (13) | 0.0410 (5) | |
C2A | 0.3519 (3) | 0.48262 (19) | 0.65002 (14) | 0.0449 (6) | |
C3A | 0.3954 (3) | 0.58968 (17) | 0.61257 (15) | 0.0452 (5) | |
C4A | 0.5753 (3) | 0.61502 (15) | 0.60785 (13) | 0.0407 (5) | |
C5A | 0.7058 (2) | 0.52907 (15) | 0.64166 (13) | 0.0378 (5) | |
C6A | 0.6584 (2) | 0.41428 (15) | 0.67789 (13) | 0.0375 (5) | |
C7A | 0.7965 (2) | 0.22922 (15) | 0.66323 (12) | 0.0333 (4) | |
C8A | 0.7270 (3) | 0.0496 (2) | 0.55046 (19) | 0.0588 (7) | |
C9A | 0.9066 (3) | 0.0408 (2) | 0.62174 (16) | 0.0526 (6) | |
Cl1B | 1.12566 (6) | 0.18138 (5) | 1.13956 (4) | 0.0505 (1) | |
S1B | 1.35483 (8) | −0.13008 (5) | 0.75206 (4) | 0.0509 (2) | |
N1B | 1.3845 (2) | −0.19353 (14) | 0.86079 (14) | 0.0469 (5) | |
N2B | 1.2747 (2) | −0.00089 (13) | 0.78769 (11) | 0.0380 (4) | |
N3B | 1.13963 (18) | 0.19625 (12) | 0.90223 (11) | 0.0321 (3) | |
N4B | 1.32552 (18) | 0.36020 (13) | 1.01366 (12) | 0.0352 (4) | |
N5B | 1.09790 (19) | 0.40512 (13) | 0.89434 (12) | 0.0388 (4) | |
C1B | 1.2069 (2) | 0.07385 (17) | 1.05470 (13) | 0.0359 (5) | |
C2B | 1.2668 (2) | −0.03721 (19) | 1.09644 (15) | 0.0452 (6) | |
C3B | 1.3290 (2) | −0.12898 (18) | 1.03814 (16) | 0.0454 (5) | |
C4B | 1.3311 (2) | −0.11275 (15) | 0.93194 (14) | 0.0367 (4) | |
C5B | 1.26880 (19) | −0.00179 (14) | 0.88987 (12) | 0.0306 (4) | |
C6B | 1.20705 (18) | 0.09766 (14) | 0.95246 (12) | 0.0288 (4) | |
C7B | 1.18549 (19) | 0.31124 (14) | 0.93720 (12) | 0.0297 (4) | |
C8B | 1.3016 (2) | 0.49159 (16) | 1.03987 (15) | 0.0406 (5) | |
C9B | 1.1930 (2) | 0.52377 (16) | 0.93606 (16) | 0.0424 (5) | |
H8AA | 0.73030 | 0.02310 | 0.47730 | 0.0710* | |
H8BA | 0.63520 | 0.00040 | 0.57190 | 0.0710* | |
H2A | 0.23490 | 0.46520 | 0.65550 | 0.0540* | |
H9AA | 0.91290 | −0.03620 | 0.65370 | 0.0630* | |
H3A | 0.30950 | 0.64460 | 0.59070 | 0.0540* | |
H9BA | 1.00250 | 0.04780 | 0.58350 | 0.0630* | |
HN3A | 0.887 (3) | 0.368 (3) | 0.7644 (17) | 0.0720* | |
HN4A | 0.597 (3) | 0.209 (3) | 0.544 (2) | 0.0720* | |
H2B | 1.26270 | −0.04660 | 1.16630 | 0.0540* | |
H3B | 1.36890 | −0.20030 | 1.06680 | 0.0550* | |
H8AB | 1.41440 | 0.53940 | 1.05880 | 0.0490* | |
H8BB | 1.23730 | 0.50460 | 1.09690 | 0.0490* | |
H9AB | 1.11220 | 0.58780 | 0.94760 | 0.0510* | |
H9BB | 1.26870 | 0.55020 | 0.88970 | 0.0510* | |
HN3B | 1.072 (3) | 0.179 (2) | 0.8391 (15) | 0.0610* | |
HN4B | 1.370 (3) | 0.317 (2) | 1.0608 (18) | 0.0610* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Cl1A | 0.0697 (3) | 0.0577 (3) | 0.0579 (3) | 0.0072 (2) | 0.0179 (3) | 0.0245 (2) |
S1A | 0.0653 (3) | 0.0384 (3) | 0.0738 (4) | −0.0043 (2) | 0.0007 (3) | 0.0089 (2) |
N1A | 0.0690 (11) | 0.0306 (7) | 0.0500 (9) | 0.0073 (7) | −0.0036 (8) | 0.0047 (7) |
N2A | 0.0487 (9) | 0.0364 (8) | 0.0591 (10) | 0.0036 (6) | −0.0049 (7) | 0.0019 (7) |
N3A | 0.0512 (9) | 0.0320 (7) | 0.0401 (8) | 0.0131 (6) | −0.0144 (6) | 0.0016 (6) |
N4A | 0.0459 (8) | 0.0443 (8) | 0.0320 (7) | 0.0146 (6) | −0.0074 (6) | 0.0016 (6) |
N5A | 0.0450 (8) | 0.0329 (7) | 0.0348 (7) | 0.0129 (6) | −0.0057 (6) | 0.0016 (6) |
C1A | 0.0548 (10) | 0.0375 (9) | 0.0300 (8) | 0.0107 (7) | 0.0041 (7) | 0.0054 (6) |
C2A | 0.0492 (10) | 0.0483 (10) | 0.0367 (9) | 0.0146 (8) | 0.0070 (7) | 0.0002 (7) |
C3A | 0.0545 (10) | 0.0386 (9) | 0.0392 (9) | 0.0227 (8) | −0.0003 (8) | −0.0008 (7) |
C4A | 0.0570 (10) | 0.0274 (7) | 0.0320 (8) | 0.0130 (7) | −0.0048 (7) | −0.0017 (6) |
C5A | 0.0466 (9) | 0.0286 (7) | 0.0324 (8) | 0.0089 (6) | −0.0053 (6) | −0.0021 (6) |
C6A | 0.0496 (9) | 0.0305 (8) | 0.0275 (7) | 0.0119 (7) | −0.0054 (6) | 0.0008 (6) |
C7A | 0.0368 (7) | 0.0328 (7) | 0.0286 (7) | 0.0056 (6) | −0.0007 (6) | 0.0082 (6) |
C8A | 0.0549 (12) | 0.0512 (11) | 0.0555 (12) | 0.0199 (9) | −0.0183 (9) | −0.0148 (9) |
C9A | 0.0517 (11) | 0.0503 (11) | 0.0456 (10) | 0.0224 (9) | −0.0109 (8) | −0.0116 (8) |
Cl1B | 0.0461 (2) | 0.0679 (3) | 0.0390 (2) | −0.0006 (2) | 0.0148 (2) | 0.0023 (2) |
S1B | 0.0633 (3) | 0.0406 (3) | 0.0434 (3) | 0.0166 (2) | −0.0008 (2) | −0.0036 (2) |
N1B | 0.0479 (9) | 0.0308 (7) | 0.0561 (10) | 0.0076 (6) | −0.0055 (7) | 0.0050 (7) |
N2B | 0.0453 (8) | 0.0328 (7) | 0.0325 (7) | 0.0074 (6) | −0.0015 (6) | 0.0034 (5) |
N3B | 0.0340 (6) | 0.0299 (6) | 0.0288 (6) | 0.0031 (5) | −0.0030 (5) | 0.0034 (5) |
N4B | 0.0299 (6) | 0.0325 (7) | 0.0393 (7) | 0.0007 (5) | −0.0014 (5) | 0.0014 (5) |
N5B | 0.0375 (7) | 0.0281 (6) | 0.0467 (8) | 0.0076 (5) | −0.0014 (6) | 0.0007 (6) |
C1B | 0.0292 (7) | 0.0442 (9) | 0.0332 (8) | −0.0048 (6) | 0.0033 (6) | 0.0074 (7) |
C2B | 0.0396 (9) | 0.0578 (11) | 0.0386 (9) | −0.0080 (8) | 0.0012 (7) | 0.0236 (8) |
C3B | 0.0422 (9) | 0.0414 (9) | 0.0514 (10) | −0.0022 (7) | −0.0029 (8) | 0.0246 (8) |
C4B | 0.0309 (7) | 0.0293 (7) | 0.0456 (9) | −0.0014 (6) | −0.0057 (6) | 0.0100 (6) |
C5B | 0.0280 (7) | 0.0273 (7) | 0.0330 (7) | −0.0019 (5) | −0.0034 (5) | 0.0065 (6) |
C6B | 0.0243 (6) | 0.0293 (7) | 0.0304 (7) | −0.0020 (5) | −0.0012 (5) | 0.0056 (5) |
C7B | 0.0265 (6) | 0.0311 (7) | 0.0312 (7) | 0.0037 (5) | 0.0052 (5) | 0.0016 (6) |
C8B | 0.0336 (8) | 0.0370 (8) | 0.0477 (10) | −0.0001 (6) | 0.0066 (7) | −0.0087 (7) |
C9B | 0.0403 (9) | 0.0292 (8) | 0.0560 (11) | 0.0053 (6) | 0.0071 (7) | 0.0007 (7) |
Cl1A—C1A | 1.734 (2) | C1A—C2A | 1.424 (3) |
Cl1B—C1B | 1.7412 (18) | C1A—C6A | 1.373 (3) |
S1A—N2A | 1.6114 (18) | C2A—C3A | 1.359 (3) |
S1A—N1A | 1.605 (2) | C3A—C4A | 1.415 (3) |
S1B—N2B | 1.6145 (16) | C4A—C5A | 1.434 (3) |
S1B—N1B | 1.6148 (18) | C5A—C6A | 1.434 (2) |
N1A—C4A | 1.345 (3) | C8A—C9A | 1.520 (3) |
N2A—C5A | 1.338 (2) | C2A—H2A | 0.9300 |
N3A—C7A | 1.290 (2) | C3A—H3A | 0.9300 |
N3A—C6A | 1.384 (2) | C8A—H8AA | 0.9700 |
N4A—C7A | 1.375 (2) | C8A—H8BA | 0.9700 |
N4A—C8A | 1.453 (3) | C9A—H9BA | 0.9700 |
N5A—C7A | 1.344 (2) | C9A—H9AA | 0.9700 |
N5A—C9A | 1.436 (3) | C1B—C6B | 1.379 (2) |
N3A—HN3A | 0.92 (2) | C1B—C2B | 1.428 (3) |
N4A—HN4A | 0.86 (3) | C2B—C3B | 1.349 (3) |
N1B—C4B | 1.343 (2) | C3B—C4B | 1.412 (3) |
N2B—C5B | 1.339 (2) | C4B—C5B | 1.434 (2) |
N3B—C7B | 1.296 (2) | C5B—C6B | 1.437 (2) |
N3B—C6B | 1.376 (2) | C8B—C9B | 1.524 (3) |
N4B—C8B | 1.460 (2) | C2B—H2B | 0.9300 |
N4B—C7B | 1.366 (2) | C3B—H3B | 0.9300 |
N5B—C9B | 1.457 (2) | C8B—H8AB | 0.9700 |
N5B—C7B | 1.351 (2) | C8B—H8BB | 0.9700 |
N3B—HN3B | 0.88 (2) | C9B—H9AB | 0.9700 |
N4B—HN4B | 0.84 (2) | C9B—H9BB | 0.9700 |
N1A—S1A—N2A | 101.46 (9) | N4A—C8A—H8BA | 111.00 |
N1B—S1B—N2B | 101.08 (8) | C9A—C8A—H8AA | 111.00 |
S1A—N1A—C4A | 105.99 (15) | C9A—C8A—H8BA | 111.00 |
S1A—N2A—C5A | 106.15 (13) | N4A—C8A—H8AA | 111.00 |
C6A—N3A—C7A | 120.01 (15) | H8AA—C8A—H8BA | 109.00 |
C7A—N4A—C8A | 108.65 (16) | H9AA—C9A—H9BA | 109.00 |
C7A—N5A—C9A | 111.44 (15) | C8A—C9A—H9BA | 111.00 |
C6A—N3A—HN3A | 120.0 (19) | C8A—C9A—H9AA | 111.00 |
C7A—N3A—HN3A | 118.9 (18) | N5A—C9A—H9AA | 111.00 |
C8A—N4A—HN4A | 121 (2) | N5A—C9A—H9BA | 111.00 |
C7A—N4A—HN4A | 119.2 (19) | Cl1B—C1B—C6B | 119.74 (13) |
S1B—N1B—C4B | 106.09 (12) | C2B—C1B—C6B | 123.76 (16) |
S1B—N2B—C5B | 106.29 (11) | Cl1B—C1B—C2B | 116.49 (13) |
C6B—N3B—C7B | 123.72 (14) | C1B—C2B—C3B | 122.33 (17) |
C7B—N4B—C8B | 108.92 (13) | C2B—C3B—C4B | 117.52 (17) |
C7B—N5B—C9B | 110.47 (14) | C3B—C4B—C5B | 120.03 (15) |
C6B—N3B—HN3B | 117.1 (14) | N1B—C4B—C3B | 126.69 (16) |
C7B—N3B—HN3B | 118.8 (14) | N1B—C4B—C5B | 113.27 (15) |
C7B—N4B—HN4B | 119.4 (15) | N2B—C5B—C6B | 124.10 (14) |
C8B—N4B—HN4B | 120.4 (15) | C4B—C5B—C6B | 122.63 (14) |
C2A—C1A—C6A | 124.01 (18) | N2B—C5B—C4B | 113.27 (14) |
Cl1A—C1A—C6A | 119.56 (15) | N3B—C6B—C1B | 128.30 (15) |
Cl1A—C1A—C2A | 116.43 (17) | N3B—C6B—C5B | 117.62 (14) |
C1A—C2A—C3A | 121.3 (2) | C1B—C6B—C5B | 113.69 (14) |
C2A—C3A—C4A | 117.99 (19) | N3B—C7B—N4B | 129.45 (15) |
N1A—C4A—C3A | 126.55 (19) | N4B—C7B—N5B | 108.75 (14) |
N1A—C4A—C5A | 113.2 (2) | N3B—C7B—N5B | 121.71 (14) |
C3A—C4A—C5A | 120.22 (16) | N4B—C8B—C9B | 101.13 (14) |
C4A—C5A—C6A | 121.60 (15) | N5B—C9B—C8B | 101.10 (14) |
N2A—C5A—C6A | 125.17 (15) | C1B—C2B—H2B | 119.00 |
N2A—C5A—C4A | 113.17 (16) | C3B—C2B—H2B | 119.00 |
N3A—C6A—C1A | 125.98 (16) | C2B—C3B—H3B | 121.00 |
N3A—C6A—C5A | 118.99 (14) | C4B—C3B—H3B | 121.00 |
C1A—C6A—C5A | 114.83 (15) | N4B—C8B—H8AB | 112.00 |
N3A—C7A—N5A | 122.83 (15) | N4B—C8B—H8BB | 112.00 |
N3A—C7A—N4A | 128.44 (16) | C9B—C8B—H8AB | 112.00 |
N4A—C7A—N5A | 108.66 (14) | C9B—C8B—H8BB | 112.00 |
N4A—C8A—C9A | 102.08 (17) | H8AB—C8B—H8BB | 109.00 |
N5A—C9A—C8A | 101.67 (17) | N5B—C9B—H9AB | 112.00 |
C1A—C2A—H2A | 119.00 | N5B—C9B—H9BB | 112.00 |
C3A—C2A—H2A | 119.00 | C8B—C9B—H9AB | 112.00 |
C2A—C3A—H3A | 121.00 | C8B—C9B—H9BB | 112.00 |
C4A—C3A—H3A | 121.00 | H9AB—C9B—H9BB | 109.00 |
N2A—S1A—N1A—C4A | −0.35 (15) | C2A—C1A—C6A—C5A | 0.8 (2) |
N1A—S1A—N2A—C5A | 0.49 (16) | Cl1A—C1A—C2A—C3A | −178.11 (15) |
N2B—S1B—N1B—C4B | −0.13 (13) | C6A—C1A—C2A—C3A | 1.2 (3) |
N1B—S1B—N2B—C5B | 0.42 (13) | Cl1A—C1A—C6A—C5A | −179.89 (12) |
S1A—N1A—C4A—C5A | 0.10 (18) | C1A—C2A—C3A—C4A | −1.7 (3) |
S1A—N1A—C4A—C3A | −179.03 (15) | C2A—C3A—C4A—C5A | 0.2 (3) |
S1A—N2A—C5A—C6A | 176.96 (14) | C2A—C3A—C4A—N1A | 179.23 (18) |
S1A—N2A—C5A—C4A | −0.48 (19) | C3A—C4A—C5A—N2A | 179.45 (17) |
C6A—N3A—C7A—N4A | 10.0 (3) | C3A—C4A—C5A—C6A | 1.9 (3) |
C7A—N3A—C6A—C5A | −115.36 (18) | N1A—C4A—C5A—N2A | 0.3 (2) |
C7A—N3A—C6A—C1A | 70.1 (2) | N1A—C4A—C5A—C6A | −177.28 (16) |
C6A—N3A—C7A—N5A | −173.51 (15) | C4A—C5A—C6A—N3A | −177.48 (15) |
C8A—N4A—C7A—N3A | −169.83 (18) | N2A—C5A—C6A—C1A | −179.54 (17) |
C7A—N4A—C8A—C9A | −24.8 (2) | C4A—C5A—C6A—C1A | −2.3 (2) |
C8A—N4A—C7A—N5A | 13.3 (2) | N2A—C5A—C6A—N3A | 5.3 (3) |
C7A—N5A—C9A—C8A | −20.2 (2) | N4A—C8A—C9A—N5A | 26.1 (2) |
C9A—N5A—C7A—N3A | −171.84 (17) | Cl1B—C1B—C6B—N3B | −4.3 (2) |
C9A—N5A—C7A—N4A | 5.3 (2) | C2B—C1B—C6B—C5B | 1.7 (2) |
S1B—N1B—C4B—C5B | −0.18 (17) | C6B—C1B—C2B—C3B | −0.1 (3) |
S1B—N1B—C4B—C3B | 178.69 (15) | Cl1B—C1B—C6B—C5B | −176.84 (11) |
S1B—N2B—C5B—C6B | 179.30 (13) | C2B—C1B—C6B—N3B | 174.28 (16) |
S1B—N2B—C5B—C4B | −0.57 (17) | Cl1B—C1B—C2B—C3B | 178.50 (14) |
C7B—N3B—C6B—C1B | 55.9 (2) | C1B—C2B—C3B—C4B | −0.9 (3) |
C7B—N3B—C6B—C5B | −131.72 (16) | C2B—C3B—C4B—N1B | −178.73 (17) |
C6B—N3B—C7B—N5B | −170.11 (15) | C2B—C3B—C4B—C5B | 0.1 (2) |
C6B—N3B—C7B—N4B | 13.9 (3) | N1B—C4B—C5B—N2B | 0.5 (2) |
C8B—N4B—C7B—N5B | 14.92 (18) | N1B—C4B—C5B—C6B | −179.36 (14) |
C7B—N4B—C8B—C9B | −28.11 (16) | C3B—C4B—C5B—N2B | −178.44 (15) |
C8B—N4B—C7B—N3B | −168.70 (16) | C3B—C4B—C5B—C6B | 1.7 (2) |
C7B—N5B—C9B—C8B | −22.90 (17) | C4B—C5B—C6B—C1B | −2.5 (2) |
C9B—N5B—C7B—N3B | −170.68 (15) | N2B—C5B—C6B—C1B | 177.67 (15) |
C9B—N5B—C7B—N4B | 6.04 (19) | C4B—C5B—C6B—N3B | −175.91 (14) |
Cl1A—C1A—C6A—N3A | −5.1 (2) | N2B—C5B—C6B—N3B | 4.2 (2) |
C2A—C1A—C6A—N3A | 175.59 (17) | N4B—C8B—C9B—N5B | 29.36 (15) |
D—H···A | D—H | H···A | D···A | D—H···A |
N3A—HN3A···N5B | 0.92 (2) | 2.10 (2) | 3.003 (2) | 168 (3) |
N4A—HN4A···N1Ai | 0.86 (3) | 2.38 (3) | 3.205 (3) | 160 (2) |
N3B—HN3B···N5A | 0.88 (2) | 1.98 (2) | 2.864 (2) | 177 (2) |
N4B—HN4B···Cl1B | 0.84 (2) | 2.75 (2) | 3.1927 (15) | 114 (2) |
N4B—HN4B···N1Bii | 0.84 (2) | 2.48 (2) | 3.227 (2) | 150 (2) |
Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) −x+3, −y, −z+2. |
Experimental details
Crystal data | |
Chemical formula | C9H8ClN5S |
Mr | 253.72 |
Crystal system, space group | Triclinic, P1 |
Temperature (K) | 296 |
a, b, c (Å) | 7.6927 (3), 10.8558 (4), 12.9969 (5) |
α, β, γ (°) | 95.790 (1), 101.126 (1), 92.192 (1) |
V (Å3) | 1057.69 (7) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.54 |
Crystal size (mm) | 0.29 × 0.18 × 0.08 |
Data collection | |
Diffractometer | Bruker APEXII CCD diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 17897, 5104, 4449 |
Rint | 0.024 |
(sin θ/λ)max (Å−1) | 0.667 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.042, 0.120, 1.03 |
No. of reflections | 5104 |
No. of parameters | 302 |
No. of restraints | 5 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.65, −0.43 |
Computer programs: APEX2 (Bruker, 2007), SAINT (Bruker, 2007), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 1997), WinGX (Farrugia, 1999) and PLATON (Spek, 2009).
D—H···A | D—H | H···A | D···A | D—H···A |
N3A—HN3A···N5B | 0.92 (2) | 2.10 (2) | 3.003 (2) | 168 (3) |
N4A—HN4A···N1Ai | 0.86 (3) | 2.38 (3) | 3.205 (3) | 160 (2) |
N3B—HN3B···N5A | 0.88 (2) | 1.98 (2) | 2.864 (2) | 177.2 (19) |
N4B—HN4B···Cl1B | 0.84 (2) | 2.75 (2) | 3.1927 (15) | 114.4 (19) |
N4B—HN4B···N1Bii | 0.84 (2) | 2.48 (2) | 3.227 (2) | 150 (2) |
Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) −x+3, −y, −z+2. |
Acknowledgements
The authors are grateful to the Higher Education Commission (HEC), Pakistan, for providing funds for the single-crystal XRD facilities at GC University, Lahore.
References
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Tizanidine {or (5-chloro-N-(4,5-dihydro-1H-imidazol-2-yl)-2,1,3-benzothiadiazol-4-amine)} is an adrenergic agonist and proved to be an active myotonolytic skeletal muscle relaxant with a chemical structure different from other muscle relaxants (Koch et al., 1989; Tse et al., 1987). It also reduces increased muscle tone associated with spasticity in patients with multiple sclerosis or spinal cord injury (Shellenberger et al., 1999). Herein, we report the crystal structure of Tizanidine.
The title compound crystallized with two unique molecules A and B in the asymmetric unit (Fig. 1). The benzothiadiazole ring systems (S1A/N1A/N2A/C1A–C6A and S1B/N1B/N2B/C1B) of both molecules A and B are essentially planar [max. deviations = 0.021 (2) Å for C5A in molecule A and 0.022 (1) Å for C6B in molecule B] and they form dihedral angles of 68.78 (9) and 54.39 (8)°, respectively, with the mean planes of their 4,5-dihydro-1H-imidazole rings (N4A/N5A/C7A–C9A and N4B/N5B/C7B–C9B). The conformations of molecules A and B are similar (Fig. 2).
Molecular conformations in the crystal structure are stabilized by intramolecular N—H···N and N—H···Cl interactions (Table 1). Both molecules A and B are forming centrosymmetric dimers through π-stacking of their benzothiadiazole rings with interplanar distances of 3.3174 (7) and 3.2943 (6) Å [Cg1···Cg2ii = 3.6026 (10) Å and Cg3···Cg4iv = 3.5096 (9) Å; symmetry codes: (i) 1-x, 1-y, 1-z; (ii) 3-x, -y, 2-z; Cg1, Cg2, Cg3 and Cg4 are the centroids of the S1A/N1A/N2A/C4A/C5A, C1A–C6A, S1B/N1B/N2B/C4B/C5B and C1B–C6B rings, respectively]. These dimers are further tied together via pairs of N—H···N hydrogen-bonds with the dihydroimidazole rings as the hydrogen bonding donor (Table 1 and Fig. 3) and one of the benzothiadiazole N atoms as the acceptor, generating rings of graph set motifs of the type R22(16) (Bernstein et al., 1995). The A2 and B2 dimers do in turn form additional N—H···N hydrogen-bonds, with the secondary amine as the H donor and the dihydroimidazole N atom as the acceptor. These R22(8) type interactions connect the A2 and B2 dimers with each other to form infinite chains that stretch along the (1 -1 1) direction of the unit cell (Fig. 3).