Tris(1,10-phenanthroline-κ2 N,N′)iron(II) bis(1,1-dicyano-2-ethoxy-2-oxoethanide)

The title compound, [Fe(C12H8N2)3](C6H5N2O2)2, consists of one [Fe(phen)3]2+ cation (phen = 1,10-phenanthroline) and two 1,1-dicyano-2-ethoxy-2-oxoethanide anions. Five atoms of the anion are disordered over two positions [site occupancy = 0.521 (13) for the major component]. In the complex cation, the FeII atom is coordinated by six N atoms from three phen ligands in a distorted octahedral geometry. Two intramolecular C—H⋯N hydrogen bonds occur in the complex cation. The crystal structure is mainly stabilized by Coulombic interactions. Weak intermolecular C—H⋯N interactions are also observed.


Zhan-Mao Cai and Shu-Zhong Zhan Comment
Tetracyanoethylene(TCNE) molecule is one of the most versatile organic compounds as it is used in a many different of reactions (Kaim & Moscherosch, 1994), due to its very low-lying p* orbital. Our interest focus on the reactivity of TCNE and transitionmetal complexes to form discrete as well as polymeric charge-transfer compoundsin which the donors and acceptors are coordinated through nitrile positions. With this mind, we have tried the reaction of FeCl 3 ×6H 2 O, 1,10phenanthroline and TCNE, surprisingly, the title complex {[Fe II (phen) 3 ][(NC) 2 C-CO 2 C 2 H 5 ]} is obtained. In the presence of H 2 O, TCNE can react with ethanol to give dicyanoethylacetate anion-radical (Lv, et al., 2008). The title complex consists of one [Fe II (phen) 3 ] 2+ cation, and two dicyanoethylacetate anion-radical. The CN distances are normal range from 1.139 (5) to 1.154 (5) Å. The average C-CN distance of 1.400 (6) Å is 0.035 Å shorter than that observed for the free TCNE (1.435 Å) (Drück & Güth, 1982). The NC-C-CN bond angle are 118.5 (3) and 122.5 (4) o , which are longer than observed in free TCNE (116.5 (12) o ) in accord with its sp 2 central carbon atom (Miller, 2006;Lv, et al., 2008). In the cation, the Fe II atom is coordinated by six N atoms from three phen ligands in a distorted octahedral geometry.The average bond length of Fe-N is 1.973 (3) Å and similar to tris(1,10-phenanthroline-2 N,N′)iron(II) squarate octahydrate (Uçar, et al., 2005) as representative example.The crystal structure is mainly stabilized by coulombic interactions. Weak C-H ···N and C-H ···F interactions are also observed, See Table 1.

Experimental
After addition of tetracyanoethylene (0.261 g, 2 mmol) in ethanol (10 ml) to the solution containing FeCl 3 ×6H 2 O(0.270 g, 1 mmol) and 1,10-phenanthroline (phen)(0.400 g, 2 mmol) in ethanol (10 ml), the mixture was stirred at room temperature for 1 h. The solution color turned from red to brown. Single crystals were obtained from the filtrate which was allowed to stand at room temperature for several days, collected by filtration, and dried in vacuo (0.26 g, 29.5%).

Figure 1
ORTEP view of the title compound, at the 30% probability level.

Crystal data
[Fe (C 12

Special details
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'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 > 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.