Abstract: The crystal structure of [CoCl(C₇H₅N₂CH₂COPh)₄]Br has been determined by means of X-ray crystallography. The molecular structure consists of a discrete [CoCl(C₇H₅N₂CH₂COPh)₄]⁺ cation and one Br^- anion. In the [CoCl(C₇H₅N₂CH₂COPh)₄]⁺ cation, the coordination geometry of the central Co atom is square-pyramidal with four tertiary N atoms of benzimidazole from four α-(benzimidazol-1-yl)-hypnone ligands in the basal position and one chloride anion in the apical position. In the solid state, [CoCl(C₇H₅N₂CH₂COPh)₄]⁺ and Br^- anion possess intermolecular and intramolecular interactions, which stabilize the crystal structure. The characterization of the title compound were also carried out by using elemeutal analysis, FTIR, UV spectrometries and TG-DSC.

Key words: α-(1-Benzimidazolyl)-hypnone ligand, Cobalt(Ⅱ) complex, Mixed Cl^- and Br^- anion, TG-DSC