No abstract

Intervalence-transfer (IT) bands at all of the mixed-valence states of oligo(1,1Ј-dihexylferrocenylene)s from the dimer to the hexamer, 2-6, were determined by analysis of the absorption spectra of the oligomers oxidized quantitatively with 1,1Ј-dichloroferrocenium hexafluorophosphate, 1, in CH 2 Cl 2 -acetone. Characteristic features of the IT bands are a higher energy shift in ν max as the oxidation number for each oligomer increases and a lower energy shift in ν max for the monocationic forms of the oligomers as the number of ferrocene units increases. A simple analysis of the shift in ν max of IT bands was made based on a model assuming that the mixed-valence states are a linear combination of reduced (Red) and oxidized (Ox) nuclei. It is qualitatively rationalized by taking into account the change in neighboring-site combination, especially between Red-Ox and Ox-Ox, formed by photoelectron transfer, which requires extra energy due to the strain in internuclear distance.