Heterohexanuclear (Cu3Fe3) complexes of substituted hexaazatrinaphthylene (HATN) ligands: twofold BF4(-) association in the solid and stepwise oxidation (3e) or reduction (2e) to spectroelectrochemically characterized species.
New tris(ferrocenylcopper) compounds [(mu(3)-dqp){Cu(dppf)}(3)][X](3) (dppf = 1,1'-bis(diphenylphosphinoferrocene), dqp = hexamethyl-, hexachloro- or un-substituted diquinoxalino[2,3-a:2',3'-c]phenazine = hexaazatrinaphthylene (HATN), X(-) = BF(4)(-) or PF(6)(-)) undergo at least two different, reversible one-electron reductions and three very closely spaced one-electron oxidations. While the latter are attributed to the stepwise ferrocene-->ferrocenium conversions, the first electron addition 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) spectroelectrochemistry (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 compound with unsubstituted dqp shows notable deviation from the trigonal symmetry and the close association of two tetrafluoroborate anions with the complex trication along the quasi-trigonal axis to yield [(mu(3)-dqp){Cu(dppf)}(3)(BF(4))(2)]BF(4).
Roy
Sayak
S
Institut für Anorganische Chemie, Universität Stuttgart, Pfaffenwaldring 55, 70550 Stuttgart, Germany.
Sarkar
Biprajit
B
Duboc
Carole
C
Fiedler
Jan
J
Sarper
Orkan
O
Lissner
Falk
F
Mobin
Shaikh M
SM
Lahiri
Goutam Kumar
GK
Kaim
Wolfgang
W
D001881:Borates; D001888:Boric Acids / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004563:Electrochemistry; D005296:Ferrous Compounds / Q000737:chemistry*; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D000075163:Metallocenes; D015394:Molecular Structure; D009281:Naphthalenes / Q000737:chemistry*; D010084:Oxidation-Reduction
D001881:Borates; D001888:Boric Acids; D005296:Ferrous Compounds; D008024:Ligands; D000075163:Metallocenes; D009281:Naphthalenes; D003300:Copper; C098759:fluoroboric acid; C004998:ferrocene