Tris[2-(1H-imidazol-2-yl)imidazol-1-ido]cobalt(III)

In the title compound, [Co(C6H5N4)3], the CoIII atom adopts a distorted octahedral CoN6 coordination geometry, arising from three N,N′-bidentate deprotonated 2,2′-biimidazole ligands. The dihedral angles between the five-membered rings of the ligands are 4.1 (2), 9.4 (2) and 10.5 (2)°. In the crystal, molecules are linked by N—H⋯N hydrogen bonds, generating a layered network lying in (11).

is reported here.

Experimental
CoCl 2 .6H 2 O (0.1904 g, 0.8 mmol), biimidazole (0.107 g, 1 mmol), and water (10 ml) were added to an aqueous solution (5 ml) containing NaN 3 (0.028 g,0.4 mmol). The resulting mixture was further stirred for 15 min in air, and then transferred and sealed in a 20 ml Teflon-lined reactor, which was heated at 423 K for 4 days and then cooled to room temperature at a rate of 5 K h -1 . Red blocks of (I) were obtained and washed with water.

Refinement
H atoms attached to C and N atoms of (I) were placed in geometrically idealized positions (C-H = 0.93Å, N-H = 0.86Å and constrained to ride on their parent atoms. Fig. 1. A view of the structure of (I) with displacement ellipsoids drawn at the 30% probability level.

Figures
supplementary materials sup-2 Crystal data [Co(C 6

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 > σ(F 2 ) is used only for calculating Rfactors(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