Département de chimie moléculaire

New tris(ferrocenylcopper) compds. [($μ$3-dqp){\{}Cu(dppf){\}}3][X]3 [dppf = 1,1'-bis(diphenylphosphinoferrocene); dqp = hexamethyl-, hexachloro- or unsubstituted diquinoxalino[2,3-a:2',3'-c]phenazine = hexaazatrinaphthylene (HATN); X- = BF4- or PF6-] undergo at least two different, reversible one-electron redns. and three very closely spaced one-electron oxidns. While the latter are attributed to the stepwise ferrocene ferrocenium conversions, the first electron addn. occurs in the ligand bridge to yield EPR detectable radical complexes. X-band EPR measurements at 9.5 GHz showed a partially resolved hyperfine structure, while high-frequency EPR measurements at 95 or 115 GHz revealed a small but variable axial g tensor anisotropy. All reversible steps were investigated by optically transparent thin-layer electrode (OTTLE) spectroelectrochem. (UV/Vis/NIR regions), revealing very low energy transitions for the reduced forms in agreement with the frontier MO arrangement. A crystal structure of the compd. with unsubstituted dqp shows notable deviation from the trigonal symmetry and the close assocn. of two tetrafluoroborate anions with the complex trication along the quasi-trigonal axis to yield [($μ$3-dqp){\{}Cu(dppf){\}}3(BF4)2]BF4. [on SciFinder(R)]