Mono- and dinuclear Cu^II complexes of the benzyldipicolylamine (BDPA) ligand: crystal structure, synthesis and characterization

The crystal structures of mono- and dinuclear Cu^II trifluoromethanesulfonate (triflate) complexes with benzyldipicolylamine (BDPA) are described. From equimolar amounts of Cu(triflate)₂ and BDPA, a water-bound Cu^II mononuclear complex, aqua(benzyldipicolylamine-κ³N,N′,N′′)bis(trifluoromethanesulfonato-κO)copper(II) tetrahydrofuran monosolvate, [Cu(CF₃SO₃)₂(C₁₉H₁₉N₃)(H₂O)]·C₄H₈O, (I), and a triflate-bridged Cu^II dinuclear complex, bis(μ-trifluoromethanesulfonato-κ²O:O′)bis[(benzyldipicolylamine-κ³N,N′,N′′)(trifluoromethanesulfonato-κO)copper(II)], [Cu₂(CF₃SO₃)₄(C₁₉H₁₉N₃)₂], were synthesized. The presence of residual moisture in the reaction medium afforded water-bound complex (I), whereas dinuclear complex (II) was synthesized from an anhydrous reaction medium. Single-crystal X-ray structure analysis reveals that the Cu^II centres adopt slightly distorted octahedral geometries in both complexes. The metal-bound water molecule in (I) is involved in intermolecular O—H…O hydrogen bonds with triflate ligands and tetrahydrofuran solvent molecules. In (II), weak intermolecular C—H…F(triflate) and C—H…O(triflate) hydrogen bonds stabilize the crystal lattice. Complexes (I) and (II) were also characterized fully using FT–IR and UV–Vis spectroscopy, cyclic voltammetry and elemental analysis.