Poly[tetraamminecopper(II) bis[tris(μ2-cyanido-κ2C,N)dicuprate(I)]]: a unique Cu(I)-Cu(II) mixed-valence complex containing anionic cuprous cyanide layers and [Cu(NH3)4]2+ cations.

The title compound, {[Cu(NH(3))(4)][Cu(CN)(3)](2)}(n), features a Cu(I)-Cu(II) mixed-valence CuCN framework based on {[Cu(2)(CN)(3)](-)}(n) anionic layers and [Cu(NH(3))(4)](2+) cations. The asymmetric unit contains two different Cu(I) ions and one Cu(II) ion which lies on a centre of inversion. Each Cu(I) ion is coordinated to three cyanide ligands with a distorted trigonal-planar geometry, while the Cu(II) ion is ligated by four ammine ligands, with a distorted square-planar coordination geometry. The interlinkage between Cu(I) ions and cyanide bridges produces a honeycomb-like {[Cu(2)(CN)(3)](-)}(n) anionic layer containing 18-membered planar [Cu(CN)](6) metallocycles. A [Cu(NH(3))(4)](2+) cation fills each metallocyclic cavity within pairs of exactly superimposed {[Cu(2)(CN)(3)](-)}(n) anionic layers, but there are no cations between the layers of adjacent pairs, which are offset. Pairs of N-H···N hydrogen-bonding interactions link the N-H groups of the ammine ligands to the N atoms of cyanide ligands.