A redetermination from the original data of the crystal structure of 2-amino-4,6-di­meth­­oxy­pyrimidin-1-ium 4-amino­benzoate

The title structure, C6H9.5N3O20.5+·C7H6.5NO20.5−, which might be named schematically as 2-amino-4,6-di­meth­oxy­pyrimidine-(μ2-hydrogen)-4-amino­benzoate to indicate a bridging H atom, has been redetermined from the data published by Thanigaimani, Mu­thiah & Lynch [Acta Cryst. (2006), E62, o2976–o2978]. The improvement of the present redetermination consists in a released geometry of the primary amine groups, which were originally assumed to be planar, as well as in a redetermination of the position of the hy­droxy H atom. This H atom, whose parameters were originally constrained, turns out to be situated about the centre of the O⋯N hydrogen bond in two disordered positions with occupancies of 0.5 each.