Acta Cryst. (2011). E67, o838-o839  [ doi:10.1107/S1600536811008348 ]

5-Chloro-N-(4,5-dihydro-1H-imidazol-2-yl)-2,1,3-benzothiadiazol-4-amine (tizanidine)

P. John, I. U. Khan, M. Akkurt, M. S. Ramzan and S. Sharif

Abstract: There are two independent molecules (A and B) with similar conformations in the asymmetric unit 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-HCl hydrogen bond occurs in molecule B. In the crystal, both molecules form centrosymmetric dimers through -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-HN 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-HN 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].

Online 12 March 2011

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