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

Two copper complexes (17)Fnac(2)Cu(C6H6) (3) and (17)Fnac(2)CuCO (4) containing the monoanionic, perfluorinated beta-diketiminate (17)Fnac(2)(-)ligand (1) ((17)Fnac(2) = FC[C(CF3)N(C6F5)](2)) were synthesized and characterized by IR and NMR spectroscopy (H-1,C-13,F-19), cyclovaltammometry (CV), elemental analysis and single crystal X-ray diffraction. The perfluorinated (17)Fnac(2)(-)ligand marginally reduces the pi-back-bonding capacity of the copper centre to the carbonyl group in 4 when compared with the corresponding (16)Fnac(2)(-)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 beta-diketimine ligands on the electronic nature of the corresponding copper complexes is discussed.