Acta Crystallographica Section C

Crystal Structure Communications

Volume 61, Part 7 (July 2005)

organic compounds

gd1394 scheme

Acta Cryst. (2005). C61, o427-o430 [doi:10.1107/S0108270105015891]

Stereochemical basis for activity in thiadiazole anticonvulsants: 1-[5-(biphenyl-2-yl)-1,3,4-thiadiazol-2-yl]methanaminium chloride and two inactive analogues, 2-(biphenyl-4-yl)-5-[2-(1-methylethylidene)hydrazino]-1,3,4-thiadiazole and the methanol solvate of its hydrochloride salt

A. Camerman, A. Hempel, D. Mastropaolo and N. Camerman

Abstract: In 1-[5-(biphenyl-2-yl)-1,3,4-thiadiazol-2-yl]methanaminium chloride, C₁₅H₁₄N₃S⁺·Cl^-, the protonation occurs at the amine N atom. The outer phenyl ring makes an angle of 88.0 (2)° with the plane through the inner benzene ring, and the planes of the thiadiazole ring and the attached benzene ring intersect at an angle of 165.5 (4)°. In addition to classical N-HN and N-HCl^- hydrogen bonds producing chains parallel to the c axis, there are weak C-HN and C-HCl^- hydrogen bonds. The hydrogen bonds and packing interactions result in hydrophilic and hydrophobic planar areas in the crystal, perpendicular to the a axis. Stereochemical comparison with phenytoin shows that the two compounds may utilize similar mechanisms of action. 2-(Biphenyl-4-yl)-5-[2-(1-methylethylidene)hydrazino]-1,3,4-thiadiazole, C₁₇H₁₆N₄S, where Z' = 2, and the methanol solvate of its hydrochloride salt, 5-(biphenyl-4-yl)-2-[2-(1-methylethylidene)hydrazino]-1,3,4-thiadiazol-3-ium chloride methanol solvate, C₁₇H₁₇N₄S⁺·Cl^-·CH₃OH, adopt linear almost planar molecular conformations. The para position of the outer phenyl ring in these compounds precludes adoption of the phenytoin anticonvulsant stereochemistry.

Formula: C₁₅H₁₄N₃S⁺·Cl^-, C₁₇H₁₆N₄S and C₁₇H₁₇N₄S⁺·Cl^-·CH₄O


	Structure factor file (CIF format) (74.8 kbytes) Contains datablock I

	Structure factor file (CIF format) (260.6 kbytes) Contains datablock II

	Structure factor file (CIF format) (155.4 kbytes) Contains datablock III

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