Poly[[aquabis(mu(2)-isonicotinato-kappa(3)N:O,O')cadmium(II)] 1,4-di-3-pyridyl-2,3-diaza-1,3-butadiene hemisolvate].

The title compound, {[Cd(C(6)H(4)NO(2))(2)(H(2)O)] x 0.5C(12)H(10)N(4)}(n), presents an intricate three-dimensional network with cavities traversing it in three orthogonal directions, where the (disordered) guest molecules lodge. The compound is a member of a series of coordination polymers presenting the same main host framework but with guests of variable size and geometry, to which the flexible skeleton seems to adapt. The disorder in the structure is explained in terms of an apparently well defined specificity in the position/orientation of the guest molecules, as determined by the main framework.