Crystal structure and spectroscopy of bis-[bis(2-benzimidazolyl)propane]copper(II) bis(triflate)monohydrate, a copper complex with a geometry intermediate between tetrahedral and square planar

The structure of a mononuclear copper(II) compound with the ligand bis(2-benzimidazolyl)propane (abbreviated as tbz) is reported. The compound [Cu(tbz)₂](CF₃SO₃)₂(H₂O) crystallizes in the triclinic space group P, with a = 12.363(6), b = 13.218(9), c = 15.365(8) Å, = 82.74(5), = 68.04(4), = 65.30(5), and Z = 2. The Cu(II) atom has a geometry intermediate between tetrahedral and square planar, consisting of four nitrogen atoms of two tbz ligands. The Cu—N—Cu angles are about 135°, while the dihedral angle between them amounts to 62° (0° for square planar and 90° for a tetrahedron). Ligand field bands are observed at 10.2 × 10³, 13.8 × 10³, and 20.3 × 10³ cm^–1, while the most characteristic infrared vibrations of the triflate anion are observed at 1273, 1260, 1238, 1221, 1171, and 1157 cm^–1.