Acta Crystallographica Section C

Crystal Structure Communications

Volume 62, Part 2 (February 2006)

organic compounds

sq1233 scheme

Acta Cryst. (2006). C62, o107-o110 [ doi:10.1107/S0108270105037856 ]

Hydrogen-bonding patterns in trimethoprim picolinate and 2-amino-4,6-dimethylpyrimidinium picolinate hemihydrate

M. Hemamalini, P. T. Muthiah and D. E. Lynch

Abstract: In the title compounds, namely 2,4-diamino-5-[(3,4,5-trimethoxyphenyl)methyl]pyrimidin-1-ium pyridine-2-carboxylate, C₁₄H₁₉N₄O₃⁺·C₆H₄NO₂^-, (I), and 2-amino-4,6-dimethylpyrimidin-1-ium pyridine-2-carboxylate hemihydrate, C₆H₁₀N₃⁺·C₆H₄NO₂^-·0.5H₂O, (II), the trimethoprim and 2-amino-4,6-dimethylpyrimidin-1-ium cations are protonated at one of the pyrimidine N atoms. In (I), bifurcated hydrogen bonds are observed between a picolinate O atom, the protonated N atom and the 2-amino group; the graph-set designator is R₂¹(6). The pyrimidine moieties of the trimethoprim cations are centrosymmetrically paired through a pair of N-HN hydrogen bonds. In addition to the base pairing, one of the picolinate O atoms bridges the 2- and 4-amino groups on either side of the paired bases, resulting in a complementary DADA array. In (II), the carboxylate group of the picolinate anion binds with the protonated pyrimidine N atom and the 2-amino group of the pyrimidine moiety through a pair of N-HO hydrogen bonds, leading to the common ring motif R₂²(8). The water molecule, which resides on a twofold rotation axis, bridges the carboxylate group of the picolinate anion via O-HO hydrogen bonds.

Formula: C₁₄H₁₉N₄O₃⁺·C₆H₄NO₂^- and C₆H₁₀N₃⁺·C₆H₄NO₂^-·0.5H₂O


	Structure factor file (CIF format) (222.2 kbytes) [ doi:10.1107/S0108270105037856/sq1233Isup2.hkl ] Contains datablock I

	Structure factor file (CIF format) (118.0 kbytes) [ doi:10.1107/S0108270105037856/sq1233IIsup3.hkl ] Contains datablock II

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