Bis(4-aminopyridine){2,2′-[1,2-phenylenebis(nitrilomethanylylidene)]diphenolato}cobalt(III) nitrate

In the title compound, [Co(C20H14N2O2)(C5H6N2)2]NO3, the CoIII atom is coordinated in a slightly elongated octahedral geometry by the N2O2 donor set of the tetradentate Schiff base ligand and by the pyridine N atoms of two trans-arranged monodentate 4-aminopyridine molecules. The pyridine rings are aligned nearly perpendicularly to each other [dihedral angle = 82.28 (13)°]. The phenoxy rings form dihedral angles of 12.37 (12) and 12.16 (14)° with the phenylene ring. In the crystal, N—H⋯O and C—H⋯O hydrogen bonds link the ions into a three-dimensional network.

In the title compound, [Co(C 20 H 14 N 2 O 2 )(C 5 H 6 N 2 ) 2 ]NO 3 , the Co III atom is coordinated in a slightly elongated octahedral geometry by the N 2 O 2 donor set of the tetradentate Schiff base ligand and by the pyridine N atoms of two trans-arranged monodentate 4-aminopyridine molecules. The pyridine rings are aligned nearly perpendicularly to each other [dihedral angle = 82.28 (13) ]. The phenoxy rings form dihedral angles of 12.37 (12) and 12.16 (14) with the phenylene ring. In the crystal, N-HÁ Á ÁO and C-HÁ Á ÁO hydrogen bonds link the ions into a three-dimensional network.
The molecular structure of the title compound is shown in Fig. 1 (Salehi et al., 2009). In the Schiff base ligand, the C15-C20 and C45-C50 phenoxy rings are tilted with respect to the phenylene ring by 12.37 (12) and 12.16 (14)° respectively. In the crystal structure (Fig. 2), the ions are linked into a three-dimensional network by interionic N-H···O and C-H···O hydrogen bonding interactions (Table 1).

Experimental
To a mixture of the Schiff base ligand (0.108 g, 0.343 mmol ) and triethylamine (0.105 mL) in MeOH, (Co(NO 3 ) 2 .6H 2 O (0.100 g, 0.343 mmol) was added and heated to 70°C. After two hours, 4-aminopyridine (0.064 g, 0.680 mmol) was added and heating and stirring continued for two hours. The resulting dark reddish-brown solid was crystallized in aceto-

Refinement
Hydrogen atoms bound to N were located in a difference Fourier map and refined isotropically with distance restraints (N -H = 0.86-0.87 Å) and U iso (H) = 1.5U eq (N). All other H atoms were introduced at their calculated positions and were then refined as riding, with C-H = 0.93 Å and U iso (H) = 1.2U eq (N) for aromatic H atoms. The crystals of the title compound systematically diffracted very poorly, resulting in a low observed/unique reflection ratio (36%).   Partial packing diagram of the title compound showing the hydrogen bonding network (dotted lines).

Bis(4-aminopyridine){2,2′-[1,2-phenylenebis(nitrilomethanylylidene)]diphenolato}cobalt(III) nitrate
Crystal data [Co(C 20  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.

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