trans-Bis(nitrato-κO)tetrakis(1-vinyl-1H-imidazole-κN 3)copper(II)

In the title compound, [Cu(NO3)2(C5H6N2)4], the CuII ion is located on an inversion centre. It features a Jahn–Teller-distorted octahedral coordination geometry, defined by four N atoms of four 1-vinylimidazole ligands in the equatorial plane and two nitrate O atoms in the axial positions. The nitrate anion is disordered over two sets of sites in a 0.801 (6):0.199 (6) ratio. In the crystal, the complex molecules are linked by weak intermolecular C—H⋯O and C—H⋯π interactions.

In the title compound, [Cu(NO 3 ) 2 (C 5 H 6 N 2 ) 4 ], the Cu II ion is located on an inversion centre. It features a Jahn-Tellerdistorted octahedral coordination geometry, defined by four N atoms of four 1-vinylimidazole ligands in the equatorial plane and two nitrate O atoms in the axial positions. The nitrate anion is disordered over two sets of sites in a 0.801 (6): 0.199 (6) ratio. In the crystal, the complex molecules are linked by weak intermolecular C-HÁ Á ÁO and C-HÁ Á Á interactions.
The molecular structure of compound (I) (Fig. 1) is similar to those of analogous derivatives (Baran, 1999). The Cu II atom displays a Jahn-Teller distorted octahedral coordination geometry, with four N atoms from four 1-vinylimidazole ligands in the equatorial plane (with Cu-N1 and Cu-N3 bond lengths of 2.0091 (15) and 2.0147 (16) Å) and two nitrate molecules in axial positions (with Cu-O2B and Cu-O2A bond lengths of 2.531 (9) and 2.651 (3) Å). These bond lengths are comparable with those reported by Baran (1999).
The imidazole rings have a maximum deviation of 0.004 Å and 0.002 Å from planarity for atoms N2 and N3, respectively. The bond lengths and angles of the 1-vinyl-imidazole molecules in (I) show no significant differences to those of the related 2-chlorobenzoato structure (Zhao, 2008).
In the crystal structure ( Fig. 2) the molecules are linked by two intermolecular C-H···O hydrogen bonds and two C-H···π hydrogen-bonding associations (Table 1).

Experimental
Complex (I) was prepared from a mixtures of solutions containing copper(II) nitrate trihydrate (2.42 g, 10 mmol) and 1vinylimidazole (1.98 g, 20 mmol) in 20 ml ethanol. The reaction mixture was stirred for 1 h, then 20 ml dissolved succinic acid (1.18 g, 10 mmol) was added. Then the reaction mixture solution was again stirred for 30 min and finally the solution was filtered. Blue single crystals of (I) were isolated after one day. Suitable crystals of (I) for structure determination were obtained from ethanol by slow evaporation (yield %55).

Refinement
H atoms were positioned geometrically and treated using a riding model, fixing the bond lengths at 0.93 Å for the sp 2 C atoms. The displacement parameters of the H atoms were constrained with U iso (H) = 1.2U eq (C). The nitrate anion was shown to be disordered over two sets of sites in a 0.801 (6):0.199 (6) ratio.    Packing of (I).

trans-Bis(nitrato-κO)tetrakis(1-vinyl-1H-imidazole-κN 3 )copper(II)
Crystal data 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. (