Iclaprim mesylate displaying a hydrogen-bonded mol-ecular tape.

The title compound, 2,6-di-amino-5-[(2-cyclo-propyl-7,8-dimeth-oxy- 2H -1-benzo-pyran-5-yl)meth-yl]pyrimidin-1-ium methane-sulfonate, C 19 H 23 N 4 O 3 + ·CH 3 O 3 S - , is a salt made up from a protonated iclaprim mol-ecule and a mesylate anion. The pyrimidine and chromene units of the iclaprim mol-ecule form an orthogonal arrangement [inter-planar angle of 89.67 (6)°], and the 3-nitro-gen position of the pyrimidine ring is protonated. Four distinct N-H⋯O inter-actions and an additional N-H⋯N hydrogen bond connect iclaprim and mesylate mol-ecules to one another, resulting in an infinite hydrogen-bonded mol-ecular tape structure. The central section of the tape is formed by a sequence of fused hydrogen-bonded rings involving four distinct ring types.