Crystal structure of [tris-(4,4'-bi-pyridine)]-diium bis-(1,1,3,3-tetra-cyano-2-eth-oxy-propenide) trihydrate.

The title hydrated salt, CHN·2CHNO·3HO, was obtained as an unexpected product from the hydro-thermal reaction between potassium 1,1,3,3-tetra-cyano-2-eth-oxy-propenide, 4,4'-bi-pyridine and iron(II) sulfate hepta-hydrate. The cation lies across a twofold rotation axis in the space group 2/ with the other components all in general positions. In the cation, the H atom linking the pyridine units is disordered over two adjacent sites having occupancies of 0.66 (4) and 0.36 (4), as N-H⋯N and N⋯H-N. The water mol-ecules of crystallization are each disordered over two sets of atomic sites, having occupancies of 0.522 (6) and 0.478 (6) for one, and 0.34 (3) and 0.16 (3) for the other, and it was not possible to reliably locate the H atoms associated with these partial-occupancy sites. In the crystal, four independent C-H⋯N hydrogen bonds link the ionic components into a three-dimensional network.