Hydrogen-bonded supramolecular motifs in 2-amino-4,6-dimethoxypyrimidinium picrate and pyrimethaminium picrate dimethyl sulfoxide solvate.

In the crystal structures of 2-amino-4,6-dimethoxypyrimidinium 2,4,6-trinitrophenolate (picrate), C(6)H(10)N(3)O(2)(+).C(6)H(2)N(3)O(7)(-), (I), and 2,4-diamino-5-(4-chlorophenyl)-6-ethylpyrimidin-1-ium (pyrimethaminium or PMN) picrate dimethyl sulfoxide solvate, C(12)H(14)ClN(4)(+).C(6)H(2)N(3)O(7)(-).C(2)H(6)OS, (II), the 2-amino-4,6-dimethoxypyrimidine and PMN cations are protonated at one of the pyrimidine N atoms. The picrate anion interacts with the protonated cations through bifurcated N-H...O hydrogen bonds, forming R(2)(1)(6) and R(1)(2)(6) ring motifs. In (I), Z' = 2. In (II), two inversion-related PMN cations are connected through a pair of N-H...N hydrogen bonds involving the 4-amino group and the uncharged N atom of the pyrimidine ring, forming a cyclic hydrogen-bonded R(2)(2)(8) motif. In addition to the pairing, the O atom of the dimethyl sulfoxide solvent molecule bridges the 2-amino and 4-amino groups on both sides of the paired bases, resulting in a self-complementary ...DADA... array of quadruple hydrogen-bonding patterns.