Azo-bridged ferrocene oligomers

B. Redox, Optical, and Photoisomerization Properties of Azo-Bridged Ferrocene Oligomers... 

Azo-bridged ferrocene oligomers also show a marked dependence on the redox potentials and IT-band characteristics of the solvent, as is usual for class II mixed valence complexes 21,22). As for the conjugated ferrocene dimers, 2 and 241 the effects of solvents on the electron-exchange rates were analyzed on the basis of the Marcus-Hush theory, in which the t/max of the IT band depends on (l/Dop — 1 /Ds), where Dop and Ds are the solvent s optical and static dielectric constants, respectively (155-157). However, a detailed analysis of the solvent effect on z/max of the IT band of the azo-bridged ferrocene oligomers, 252,64+, and 642+, indicates that the i/max shift is dependent not only on the parameters in the Marcus-Hush theory but also on the nature of the solvent as donor or acceptor (92). 

Strong MLCT bands appear in the neutral form of azo-bridged ferrocene oligomers, as noted above. The absorption of the MLCT band at 534 nm diminishes, and a new band appears and increases at 672 nm with the oxidation to 25+. The new band can be assigned to a ligand-to-... 

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