Acta Cryst. (2004). E60, o2350-o2352  [ doi:10.1107/S1600536804028867 ]

Trimethoprim-hydrogen malonate (1/1)

M. Hemamalini, P. T. Muthiah and R. J. Butcher

Abstract: In the title compound, 2,4-diamino-5-(3,4,5-trimethoxybenzyl)pyrimidinium hydrogen malonate, C₁₄H₁₉N₄O₃⁺·C₃H₃O₄^-, the trimethoprim molecule is protonated at one of the pyrimidine N atoms. The carboxylate group of the hydrogen malonate ion accepts a pair of N-HO hydrogen bonds from an adjacent trimethoprim molecule, which is similar to the carboxylate-trimethoprim cation interaction present in the complex of dihydrofolate reductase with trimethoprim. An O atom of the carboxyl group forms an intramolecular O-HO hydrogen bond with the carboxylate group, leading to a folded conformation for the hydrogen malonate ion. Each hydrogen malonate ion bridges two diaminopyrimidine cations, via N-HO and C-HN hydrogen bonds, leading to a supramolecular ribbon made up of alternating cations and anions. Two such inversion-related ribbons are cross-linked by (amino)N-HO(methoxy) hydrogen bonds, (pyrimidine)C-HO(methoxy) hydrogen bonds and - stacking involving the benzene planes.

Online 20 November 2004

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