Electronic effect of a perfluorinated β-diketiminate ligand on the bonding nature of copper carbonyl complexes

Abstract

Two copper complexes ¹⁷Fnac₂Cu(C₆H₆) (3) and ¹⁷Fnac₂CuCO (4) containing the monoanionic, perfluorinated β-diketiminate ¹⁷Fnac₂⁻ ligand (1) (¹⁷Fnac₂ = FC[C(CF₃)N(C₆F₅)]₂) were synthesized and characterized by IR and NMR spectroscopy (¹H, ¹³C, ¹⁹F), cyclovaltammometry (CV), elemental analysis and single crystal X-ray diffraction. The perfluorinated ¹⁷Fnac₂⁻ ligand marginally reduces the π-back-bonding capacity of the copper centre to the carbonyl group in 4 when compared with the corresponding ¹⁶Fnac₂⁻ substituted complexes but substantially when compared with the fluorine free substituted derivatives. Quantum chemical calculations gave deeper insight into the bonding situation of this carbonyl complex, while CV studies were performed to determine the oxidation potential of 3 in solution. Based on these data, the influence of the degree of fluorination in different β-diketimine ligands on the electronic nature of the corresponding copper complexes is discussed.