Azaferrocenophanes with azobenzene-containing ligands -: Protonation and electrochemical oxidation of the molecule influences the absorption spectra and cis-trans isomerization of the azobenzene group

N-{4-(Phenylazo)phenyl}aminophenyl-2-aza-[3]-ferrocenophane (4) and N-{3-(phenylazo)phenyl}aminophenyl-2-aza-[3]-ferrocenophane (5) have been prepared by C-N bond-forming reactions catalyzed by Ru and Pd complexes. The absorption peaks due to the pi-pi* transition of the trans-azobenzene group of 4 and 5 appear at 442 and 426 nm, respectively, in toluene. Photoirradiation of solutions of 4 and 5 at 420 nm causes partial isomerization of the trans-azobenzene group to cis-azobenzene and reaches a photostationary state. The compounds at the photostationary state undergo thermal isomerization of the cis-azobenzene group to the trans isomer. The isomerization after one-electron oxidation of the compounds takes place more rapidly than that without electrochemical oxidation. (C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005.