4,4′-Diazenediyldipyridinium 4-(4-pyridyldiazen­yl)pyridinium octa­cyanidotungstate(V) dihydrate

The asymmetric unit of the title complex, (C(10)H(10)N(4))(C(10)H(9)N(4))[W(CN)(8)]·2H(2)O, contains two 4,4′-diazenediyldipyridinium, [H(2)(4,4′-azpy)](2+), two 4-(4-pyridyldiazen­yl)pyridinium, [H(4,4′-azpy)](+), cations, two [W(V)(CN)(8)](3−) anions, and four uncoordinated water mol­ecules. Each of the W centers is coordinated by eight CN groups in a slightly distorted square-anti­prismatic geometry. In the crystal structure, intra- and inter­molecular N—H⋯O, N—H⋯N and O—H⋯N hydrogen bonds link the cations and anions in an alternating fashion, forming a two-dimensional layered structure, in which they are further linked through the very weak π–π stacking inter­actions [shortest distance = 4.640 (2) Å] and van der Waals forces between adjacent layers, forming a three-dimensional supra­molecular network.