Synthesis, structure, and spectroscopic and electrochemical properties of copper(II/I) Complexes with symmetrical and unsymmetrical 2, 9-Diaryl-1,10-phenanthroline ligands

A series of copper(II) and copper(I) complexes, [CuX₂L] (16) and [CuL₂](CuX₂) (7-12) (X = Cl, Br; L = 2-R-9-R′-l, 10phenanthroline, dpp: R = R′ = Ph; npp: R = naphthyl, R′ = Ph; dnp: R = R′ = naphthyl) were synthesized and characterized by elemental analysis, UV/Vis and IR spectroscopy, and Xray crystal diffraction (for 1, 3, 6, and 12), The copper(II) complexes are four-coordinate with one phenanthroline ligand and two halogen atoms, whereas the copper(I) complexes are tetrahedrally coordinated by two bidentate phenanthroline ligands. Cyclic voltammetry studies of the Cu^I complexes in CH₂Cl₂ reveal that bulky groups in the 2,9-positions have significant effects on the redox potential of the Cu^II/I couple, which is more positive for the complexes with the dnp ligand than those with the dpp and npp ligands,