u-Cyano-1:2 kappa(2)C:N-tetracyano-1 kappa(4)C-(5-methyl-5-nitro-3,7-diazanonane-1,9-diamine-2 kappa(4)N(1,3,6,9))-nitrosyl-1 kappa N-copper(II)iron(II) dihydrate.

The title binuclear complex, [CuFe(CN)(5)(C(8)H(21)N(5)O(2))(NO)] x 2H(2)O or [CuFe(nelin)(CN)(5)(NO)] x 2H(2)O (nelin is 5-methyl-5-nitro-3,7-diazanonane-1,9-diamine) consists of discrete binuclear mixed-metal species, with a Cu centre linked to an Fe centre through a cyano bridge, and two water molecules of crystallization. In the complex, the Cu(II) ion is coordinated by five N atoms and has a distorted square-pyramidal geometry. The Fe(II) centre is in a distorted octahedral environment.