INFLUENCE OF ARENECHROMIUM TRICARBONYL ON THE REDOX BEHAVIOR OF COPPER IN NEW HETEROPENTANUCLEAR COMPLEXES PREPARED FROM FUNCTIONALIZED PHENANTHROLINE TWEEZER LIGANDS

Novel mixed [Cu(4a-c)2]CF3SO3 pentanuclear copper(I)/chromium(0) complexes containing tweezer ligands that contain, within the same molecule, a 2,9-disubstituted-1,10-phenanthroline and two arene-chromium subunits. The mononuclear copper(I) complexes [Cu(5a-c)2] CF3SO3 have been prepared from the chromium free ligand species 5a-c, obtained by quantitative photochemical decomplexation of the parent species 4a-c. Cyclic voltammetry showed that in these complexes copper(I) can be reversibly oxidized to copper(II) in CH2Cl2. The Cu(II/I) couples are more positive in the presence of the four surrounding redox-active arenechromium subunits, revealing an electron-withdrawing effect. Complexes [Cu(4c)2]+, [Cu(5c)2]+ form new species (1:1 ligand copper stoichiometry) upon addition of excess [Cu(CH3CN)4]+, which were identified electrochemically and by FAB+ mass spectroscopy.