Acta Cryst. (2002). E58, o59-o61  [ doi:10.1107/S1600536801020293 ]

Hydrogen-bonding patterns in trimethoprim perchlorate [trimethoprim = 2,4-diamino-5-(3,4,5-trimethoxybenzyl)pyrimidine]

P. T. Muthiah, B. Umadevi, N. Stanley, G. Bocelli and A. Cantoni

Abstract: In the title crystal, trimethoprim perchlorate [2,4-diamino-5-(3,4,5-trimethoxybenzyl)pyrimidin-1-ium perchlorate], C₁₄H₁₉N₄O₃⁺·ClO₄^-, the trimethoprim molecule is protonated at N1. The perchlorate ion makes double hydrogen bonds of type N-HO with the 2-amino group and the protonated N1 atom of the trimethoprim cation, reminiscent of the fork-like interactions of the carboxylate group with the trimethoprim (TMP) cation observed in the dihydrofolate reductase-trimethoprim complex. The pyrimidine moieties of trimethoprim cations are centrosymmetrically paired through a pair of N-HN hydrogen bonds involving the 4-amino group and the pyrimidinium-N atom. The two pairs of TMP cations are linked by N-HO hydrogen bonds to form a supramolecular ladder-like structure. The pyrimidine plane makes a dihedral angle of 83.72  (8)° with the phenyl ring in the TMP cation.

Online 14 December 2001

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