2,6-Dimethoxy-7,9-dimethylpurinium iodide hemihydrate.

In the title compound, C(9)H(13)N(4)O(2)(+) x I(-) x 0.5 H(2)O, the non-H atoms of the ionic components lie on a mirror plane in Cmca, with the O atom of the partial water molecule lying on a twofold rotation axis. Whereas one of the methoxy methyl groups is directed away from the adjacent N-methyl group, the other methoxy methyl group is directed towards its adjacent N-methyl group. The conformation of the methoxy methyl groups provides an explanation for the outcomes of intramolecular thermal rearrangements of 2,6-dialkoxy-7,9-dimethylpurinium salts.