title: Cu2(dien)2Ag5(CN)9 containing the one-dimensional polymeric cation [Cu(dien)Ag(CN)2](n+)(n) and the unusual [Ag2(CN)3]- anion (dien is diethylenetriamine).
abstract: From the 1:1 system of [Cu(dien)(2)](NO(3))(2) and K[Ag(CN)(2)] in water (dien is diethylenetriamine, C(4)H(13)N(3)), the novel compound catena-poly[bis[[mu-cyano-1:2kappa(2)C:N-diethylenetriamine-2kappa(3)N-copper(II)silver(I)]-mu-cyano-1:2'kappa(2)C:N] dicyanosilver(I) tricyanodisilver(I)], [CuAg(CN)(2)(dien)](2)[Ag(CN)(2)][Ag(2)(CN)(3)], has been isolated. The structure is formed from positively charged [-Cu(dien)-NC-Ag-CN-](n+)(n) chains and two isolated centrosymmetric [Ag(CN)(2)](-) and [Ag(2)(CN)(3)](-) anions. In the cationic chains, the Cu atoms are linked by bridging dicyanoargentate groups, and the deformed square-pyramidal coordination polyhedron of the Cu(II) cation is formed from a tridentate chelate-like bonded dien ligand and two N-bonded bridging cyano groups. One of the bridging cyano groups occupies the apical (ap) position [mean Cu-N(eq) = 2.02 (2) A, and Cu-N(ap) = 2.170 (3) A; eq is equatorial]. Short argentophilic interactions in the range 3.16-3.30 A are present in the crystal structure.