Tetrakis(μ2-cyanido-κ2 C:N)dicyanidotetrakis[tris(2-aminoethyl)amine-κ3 N,N′,N′′,N′′′]tetracopper(II)iron(II) bis[pentacyanidonitrosoferrate(II)] hexahydrate

The asymmetric unit of the title complex, [Cu4Fe(CN)6(C6H18N4)4][Fe(CN)5(NO)]2·6H2O, comprises a complex [{Cu(tren)CN}4Fe(CN)2]4+ [tren is tris(2-aminoethyl)amine] cation, which exhibits -1 symmetry with the terminal cyanide ligands oriented trans to each other, and two [Fe(CN)5(NO)]2− nitroprussiate counter-anions. In the crystal, N—H⋯N hydrogen-bonding interactions are observed between H atoms on the primary amine groups of the tren ligand and the terminal cyanide groups of the nitroprussiate counter-ions. The N atom in the terminal CN ligand of the cation is equally disordered over two positions. The structure also contains disordered lattice water molecules. Their contribution was eliminated from the refinement using the procedure described by van der Sluis & Spek (1990 ▶).

The asymmetric unit of the title complex, [Cu 4 Fe(CN) 6 -(C 6 H 18 N 4 ) 4 ][Fe(CN) 5 (NO)] 2 Á6H 2 O, comprises a complex [{Cu(tren)CN} 4 Fe(CN) 2 ] 4+ [tren is tris(2-aminoethyl)amine] cation, which exhibits 1 symmetry with the terminal cyanide ligands oriented trans to each other, and two [Fe(CN) 5 (NO)] 2À nitroprussiate counter-anions. In the crystal, N-HÁ Á ÁN hydrogen-bonding interactions are observed between H atoms on the primary amine groups of the tren ligand and the terminal cyanide groups of the nitroprussiate counter-ions. The N atom in the terminal CN ligand of the cation is equally disordered over two positions. The structure also contains disordered lattice water molecules. Their contribution was eliminated from the refinement using the procedure described by van der Sluis & Spek (1990).
The asymmetric unit contains two iron ions. One of them which is connected to copper ions by bridging cyanide groups Å, whereas, as expected, the Fe-C-N bond angles only vary in the small range between 176.1 (4)° and 176.5 (4)° (not taking into account disordered CN ligand). The Cu-N-C bond angles, on the other hand, deviate significantly from linearity and lie between 163.4 (4) and 165.0 (4)°. All bond distances and angles are comparable to the corresponding distances in closely related compounds (El Fallah et al. (1996); Lu et al. (1997); Zou et al. (1997); Parker et al. (2001)).

Refinement
All H atoms were refined using rigid model with U iso = 1.2U eq of the carrier atom. The N atom in one of the CN ligands is disordered over two positions with equal occupancy. Despite of the fact that some other atoms show high U eq or prolate U aniso , F obs map indicates single electron density peak for each atom. Thus, no disorder was introduced in the model.
Structure contains disorderes water molecules. Solvent contribution was eliminated using procedure described by van der supplementary materials sup-2 Acta Cryst. (2012). E68, m1266-m1267 Sluis and Spek (1990). Integrated number of solvent electrons per cell is 39.9, which corresponds to 4 water molecules.

Figure 1
Structure of the title compound, with displacement ellipsoids drawn at the 30% probability level for non-H atoms.
Unlabelled atoms are generated by the application of the inversion centre.  Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq Occ. (