catena-Poly[(E)-4,4′-(ethene-1,2-diyl)dipyridinium [[bis(thiocyanato-κN)ferrate(II)]-di-μ-thiocyanato-κ2 N:S;κ2 S:N]]

In the title compound, {(C12H12N2)[Fe(NCS)4]}n, each FeII cation is coordinated by four N-bonded and two S-bonded thiocyanate anions in an octahedral coordination mode. The asymmetric unit consists of one FeII cation, located on a center of inversion, as well as one protonated (E)-4,4′-(ethene-1,2-diyl)dipyridinium dication and two thiocyanate anions in general positions. The crystal structure consists of Fe—(NCS)2—Fe chains extending along the a axis, in which two further thiocyanate anions are only terminally bonded via nitrogen. Non-coordinating (E)-4,4′-(ethene-1,2-diyl)dipyridinium cations are found between the chains.

In the title compound, {(C 12 H 12 N 2 )[Fe(NCS) 4 ]} n , each Fe II cation is coordinated by four N-bonded and two S-bonded thiocyanate anions in an octahedral coordination mode. The asymmetric unit consists of one Fe II cation, located on a center of inversion, as well as one protonated (E)-4,4 0 -(ethene-1,2diyl)dipyridinium dication and two thiocyanate anions in general positions. The crystal structure consists of Fe-(NCS) 2 -Fe chains extending along the a axis, in which two further thiocyanate anions are only terminally bonded via nitrogen. Non-coordinating (E)-4,4 0 -(ethene-1,2-diyl)dipyridinium cations are found between the chains.

Structure Reports Online
The title compound of composition [Fe(NCS) 4 ] n -[E-1,2-di(4'-pyridinium)-ethene] n ( Fig. 1) represents an 1-D coordination polymer, in which each iron(II) cation is connected by four µ-1,3 bridging thiocyanato anions into chains that elongate in the direction of the crystallographic a-axis (Fig. 3). The octahedral coordination of each Fe cation is completed by two N-bonded thiocyanato anions. It must be noted that according to a search in the CCDC database (ConQuest Ver. 1. 12 2010) such chains with transition metals are unknown (Allen, 2002).

Refinement
All H atoms were located in difference map but were positioned with idealized geometry and were refined isotropic with U eq (H) = 1.2 U eq (C,N) of the parent atom using a riding model with C-H = 0.93 Å and N-H = 0.86 Å.

Special details
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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.