Crystal structure of [tris(4,4′-bipyridine)]diium bis(1,1,3,3-tetracyano-2-ethoxypropenide) trihydrate

The title hydrated salt, C30H26N6 ²⁺·2C9H5N4O^-·3H2O, was obtained as an unexpected product from the hydrothermal reaction between potassium 1,1,3,3-tetracyano-2-ethoxypropenide, 4,4′-bipyridine and iron(II) sulfate heptahydrate. The cation lies across a twofold rotation axis in the space group I2/a 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), i.e. as N - H⋯N and N⋯H - N. The water molecules 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.