Bis[2-(1H-benzimidazol-2-yl)phenolato-κ2 N 3,O]cobalt(II) dimethylformamide disolvate

In the crystal structure of the title compound, [Co(C13H9N2O)2]·2C3H7NO, the CoII ion is four-coordinated by two N atoms and two O atoms from two deprotonated 2-(1H-benzimidazol-2-yl)phenol ligands in a distorted tetrahedral geometry. The dimethylformamide solvent molecules are found inside a two-dimensional network structure formed by intermolecular N—H⋯O hydrogen bonds linking the molecules.

In the crystal structure of the title compound, [Co(C 13 H 9 -N 2 O) 2 ]Á2C 3 H 7 NO, the Co II ion is four-coordinated by two N atoms and two O atoms from two deprotonated 2-(1Hbenzimidazol-2-yl)phenol ligands in a distorted tetrahedral geometry. The dimethylformamide solvent molecules are found inside a two-dimensional network structure formed by intermolecular N-HÁ Á ÁO hydrogen bonds linking the molecules.

Comment
Complexes with imidazole-related and imidazole-containing ligands serve as models for metalloproteins and have been extensively studied in recent years (Sundburg et al., 1974;Maekawa et al., 1989;Lorosch & Haase, 1985;Benzekri et al., 1991;Crane et al., 1995;McKee et al., 1981). It has been shown in the previous reports, that the benzimidazole-based derivatives are a novel class of N,O-donor ligands that could form sublimable luminescent complexes as possible electroluminescent materials (Nalwa et al., 2003;Tong et al., 2005). The bidentate ligand 2-(2'-hydroxyphenyl)benzimidazole(hpbm) is an N,O bidentate ligand that comprises two donor groups of relevance to the coordination of metal centers in biological systems, namely phenolate (tyrosine) and imidazole (histidine). In present paper, we report the synthesis and crystal structure of the dimethylformamide solvate of the Co II complex with two deprotonated ligands, [Co(pbm) 2 ].2(DMF).
The structure of the complex is shown in Fig. 1. The molecules of the cobalt complex are disposed about a twofold symmetry axis. The Co-O and Co-N bond lengths are 1.9135 (2) Å, and 1.9784 (2)Å respectively ( Table 1) The title complex was obtained as follows: To a filtered solution of HL(0.420 g, 2 mmol) and KOH (0.112 g, 2 mmol) in methanol(60 ml) at rt was added a filtered solution of Co(OAc) 2 . H 2 O (0.250 g, 1 mmol) in methanol(29 ml) with stirring.
The product began to crystallize from the solution tardily. After 1 h the pink solid was filtered off, washed with methanol, and air-dried. X-ray quality single crystals were grown by the vapour diffusion of ether into a DMF solution of the solid above to yield pink crystals of the title complex. The H atoms on C atom were treated as riding with C-H = 0.96Å and U iso (H) = 1.5U e.g of the parent atom. The H atoms on N atom were refined with U iso (H) = 1.2U e.g of the parent atom and N-H = 0.86 Å. The final electron density maximum and minimum were +0.31 and -0.46 e Å -3 respectively. Fig. 1. A view of the molecular structure of (I) with the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level for non-hydrogen atoms. H atoms are shown as small spheres of arbitrary radii. [symmetry code: (i) -x + 1, y, -z + 1/2] Fig. 2. Two-dimensional network structure with the solvent molecules encapsulated.

Figures
Crystal data [Co(C 13