Crystal structure of 2-amino-4,6-di­meth­oxy­pyrimidinium thio­phene-2-carboxyl­ate

In the title salt, C(6)H(10)N(3)O(2) (+)·C(5)H(3)O(2)S(−), the 2-amino-4,6-di­meth­oxy­pyrimidinium cation inter­acts with the carboxyl­ate group of the thio­phene-2-carboxyl­ate anion through a pair of N—H⋯O hydrogen bonds, forming an R (2) (2)(8) ring motif. These motifs are centrosymmetrically paired via N—H⋯O hydrogen bonds, forming a complementary DDAA array. The separate DDAA arrays are linked by π–π stacking inter­actions between the pyrimidine rings, as well as by a number of weak C—H⋯O and N—H⋯O inter­actions. In the anion, the dihedral angle between the ring plane and the CO(2) group is 11.60 (3)°. In the cation, the C atoms of methoxy groups deviate from the ring plane by 0.433 (10) Å.