Bis(6-thioxo-1,6-dihydropurinium) tetrachlorozincate(II).

The title salt, (C(5)H(5)N(4)S)(2)[ZnCl(4)], consists of two 6-thioxo-1,6-dihydropurinium (6mpH(2)(+)) cations (A and B) and a tetrachlorozincate anion, which are held together by N-H...Cl and C-H...Cl interactions. There is an anion-pi interaction between one Cl atom of the [ZnCl(4)](-) anion and the pyrimidine ring of the 6mpH(2)(+)(B) cation. Intermolecular pi-pi stacking interactions allow 6mpH(2)(+)(A) cations to form antiparallel pairs. One interesting structural feature is the double N-H...N intermolecular hydrogen bonds between two 6mpH(2)(+)(A) cations. This kind of interaction, mimicking that of natural nucleobases, can be very valuable in designing new therapeutic purine derivatives.