Bis[(cyanido-κC)bis(1,10-phenanthroline-κ2 N,N′)copper(II)] pentakis(cyanido-κC)nitrosoferrate(II) dimethylformamide monosolvate

The title compound, [Cu(CN)(C12H8N2)2]2[Fe(CN)5(NO)]·C3H7NO, is formed of discrete [Cu(phen)2CN]+ cations (phen is 1,10-phenanthroline), nitroprusside [Fe(CN)5(NO)]2− anions and dimethylformamide (DMF) molecules of crystallization. The metal atom has a distorted trigonal–bipyramidal coordination environment, defined by four N atoms of two phen molecules and a C atom of the cyanide group (in the equatorial position). The [Fe(CN)5(NO)]2− anion was found to be disordered about (but not on) a crystallographic twofold rotation axis. Geometries were restrained to ideal values. The dimethylformamide solvent molecule was found to be disordered about a crystallographic inversion centre.

The title compound, [Cu(CN)(C 12 H 8 N 2 ) 2 ] 2 [Fe(CN) 5 (NO)]Á-C 3 H 7 NO, is formed of discrete [Cu(phen) 2 CN] + cations (phen is 1,10-phenanthroline), nitroprusside [Fe(CN) 5 (NO)] 2À anions and dimethylformamide (DMF) molecules of crystallization. The metal atom has a distorted trigonal-bipyramidal coordination environment, defined by four N atoms of two phen molecules and a C atom of the cyanide group (in the equatorial position). The [Fe(CN) 5 (NO)] 2À anion was found to be disordered about (but not on) a crystallographic twofold rotation axis. Geometries were restrained to ideal values. The dimethylformamide solvent molecule was found to be disordered about a crystallographic inversion centre.

Experimental
Crystal data [Cu(CN) (C 12 Table 1 Selected bond lengths (Å ). Recently, we have shown that sodium nitroprusside could be used as a source of metalloligand or could supply the second metal upon its destruction in direct synthesis of heterometallic Cu/Fe complexes (Vreshch et al., 2009a,b). Within this study we prepared a new cation-anion Cu/Fe complex based on the self-assembly of nitroprusside anion and Cu cation containing a bidentate amine.The title compound was isolated from the solution obtained by reacting copper powder and sodium nitroprusside with (NH 4 ) 2 C 2 O 4 and 1,10-phenanthroline in DMF. Obviously, the nitroprusside partially decomposed to supply a cyanide group to the cation while sodium oxalate did not participate. To the best of our knowledge the title compound has not been structurally characterized. The cyanide group occupies the remaining equatorial position with the Cu-C bond of 1.964 (4) Å. A similar coordination geometry was observed in other complexes containing [Cu(phen) 2 CN]] + cations (Dunaj-Jurčo et al., 1993;Potočňák et al., 1996a,b).
The [Fe(CN) 5 (NO)] 2anion was found to be disordered about (but not on) the crystallographic 2-fold axis. Geometries were restrained to ideal values (Soria et al., 2002): a usual distorted octahedral pagoda-like conformation of the nitroprusside anion, with Fe-C bond distances in the range 1.933 (7)-1.959 (6) Å and a Fe-N bond distance of 1.630 (6) Å.
There was no indication from the refinement of any disorder between the nitrosyl and cyanide groups.
The structure is completed by dimethylformamide solvent molecules that were found to be disordered about the crystallographic inversion centre.

Experimental
Copper powder (0.08 g, 1.25 mmol), (NH 4 ) 2 C 2 O 4 .H 2 O (0.18 g, 1.25 mmol), Na 2 [Fe(CN) 5 (NO)].2H 2 O (0.37 g, 1.25 mmol), phen.H 2 O (0.75 g, 3.77 mmol), and 20 ml DMF were heated to 323-333 K and magnetically stirred until total dissolution of the copper was observed (50 min). The resulting blue solution was filtered and allowed to stand at room temperature. Blue-green plate-like microcrystals of the title compound were formed after one day. They were collected by filter-suction, washed with dry Pr i OH and finally dried in vacuo (yield: 20%).

Refinement
The non-hydrogen atoms were refined anisotropically. Hydrogen atoms were placed at idealized positions (C-H = 0.95 Å, U iso (H) = 1.2U eq C for CH and 1.5U eq C for CH 3 ) and refined as part of riding models.

Figure 1
Molecular structure of the cation with the numbering scheme (the non-hydrogen atoms ellipsoids are shown at the 50% probability level).  Unit-cell contents of (I). Only one set of each of the disordered atoms is shown for clarity.

Special details
Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'s involving l.s. planes. 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 > 2σ(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. The Fe(CN) 5 (NO) anion was found to be disordered about (but not on) the crystallographic 2-fold axis. Geometries were restrained to ideal values. There was no indication from the refinement of any disorder between the nitrosyl and cyanide groups. The dimethylformamide solvent molecule was found to be disordered about the crystallographic inversion centre.

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