title: 4,4'-Diazenediyldipyridinium 4-(4-pyridyldiazen-yl)pyridinium octa-cyanidotungstate(V) dihydrate.
abstract: 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-pyridyldiazen-yl)pyridinium, [H(4,4'-azpy)](+), cations, two [W(V)(CN)(8)](3-) anions, and four uncoordinated water mol-ecules. Each of the W centers is coordinated by eight CN groups in a slightly distorted square-anti-prismatic geometry. In the crystal structure, intra- and inter-molecular 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 inter-actions [shortest distance = 4.640 (2) Å] and van der Waals forces between adjacent layers, forming a three-dimensional supra-molecular network.
authors.affiliation: School of Material Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, People's Republic of China.
authors.forename: Su-Yan
authors.initials: SY
authors.lastname: Qian
authors.forename: Wen-Yan
authors.initials: WY
authors.lastname: Liu
authors.forename: Ai-Hua
authors.initials: AH
authors.lastname: Yuan