(2,2′-Bipyridine-κ2 N,N′)bis(nitrato-κ2 O,O′)copper(II)

In the title complex, [Cu(NO3)2(C10H8N2)], the CuII cation is chelated by two nitrate anions and by one 2,2′-bipyridine ligand in a distorted N2O4 octahedral geometry. The dihedral angle between the pyridine rings is 1.92 (11)°. In the crystal, π–π stacking between parallel pyridine rings of adjacent complex molecules is observed, the centroid–centroid distance being 3.6788 (19) Å. Weak C—H⋯O hydrogen bonds further link the molecules into a three-dimensional supramolecular architecture.

In the title complex, [Cu(NO 3 ) 2 (C 10 H 8 N 2 )], the Cu II cation is chelated by two nitrate anions and by one 2,2 0 -bipyridine ligand in a distorted N 2 O 4 octahedral geometry. The dihedral angle between the pyridine rings is 1.92 (11) . In the crystal, stacking between parallel pyridine rings of adjacent complex molecules is observed, the centroid-centroid distance being 3.6788 (19) Å . Weak C-HÁ Á ÁO hydrogen bonds further link the molecules into a three-dimensional supramolecular architecture.

Comment
Copper(II) is one of the most important transition metals in magnetochemistry (Garribba et al. 2000;Mukherjee, 2000).

Experimental
A solution of copper(II) nitrate hydrate (0.2 mmol, 48 mg) in methanol (2 ml) was mixed with 2 ml of an aqueous solution of p-aminobenzoic acid (0.1 mmol, 17 mg) in presence of 2,2-bipyridine (0.1 mmol, 16 mg). The resulting mixture was allowed to evaporate for one week to yield a blue crystal, suitable to X-ray work.

Refinement
H atoms were geometrically fixed and allowed to ride on the non-H atom with C-H = 0.93 Å, U iso (H) = 1.2U eq (C).  The molecular structure of the title compound, with atom labels and 30% probability displacement ellipsoids.  The pi···pi stacking between two asymmetric cations.  A view of the crystal packing. Hydrogen bonds are shown as brown dashed lines.

(2,2′-Bipyridine-κ 2 N,N′)bis(nitrato-κ 2 O,O′)copper(II)
Crystal data [Cu(NO 3  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.