Crystal structure of tris(1,3-dimesityl-4,5-dihydro-1H-imidazol-3-ium) tetrabromidocobaltate(II) bromide chloroform hexasolvate

In the unit cell of the title compound, (C21H27N2)3[CoBr4]Br·6CHCl3, the tetrabromidocobaltate(II) anion and the bromide anion are located on a crystallographic threefold rotation axis. For the [CoBr4]2− group, the axis runs through one of the Br ligands and the CoII atom. All other structure moieties lie on general sites. Various tris(1,3-dimesityl-4,5-dihydro-1H-imidazol-3-ium) structures with different counter-ions have been reported. In the title compound, the N—C—N angle is 113.7 (5)°, with short C—N bond lengths of 1.297 (7) and 1.307 (7) Å. The two mesityl planes make a dihedral angle of 34.6 (1)° and the dihedral angles between the mesityl and N–C–N planes are 82.0 (1) and 88.5 (1)°, respectively. The imidazoline ring is almost planar, with atom deviations in the range 0.003 (5)–0.017 (5) Å from the best plane; the mean deviation is 0.012 (5) Å. In the crystal, non-covalent interactions of the C—H...Br type occur between the Br− anion and the cation, as well as between the [CoBr4]2− anion and both the chloroform solvent molecules. These H...A distances are slightly shorter than the sum of van der Waals radii