INTERVALENCE ELECTRON-TRANSFER IN PENTAAMMINERUTHENIUM COMPLEXES OF DIPYRIDYLPOLYENES, DIPYRIDYLTHIOPHENE, AND DIPYRIDYLFURAN

Intervalence transitions have been observed between pentaammineruthenium(II) and -ruthenium(III) groups linked by dipyridylpolyenes, dipyridylthiophene, and dipyridylfuran. For all compounds, the comproportionation constants have been determined, to obtain corrected spectra of the mixed-valence forms, and the intervalence band profiles have been obtained by spectral deconvolution. The longest dipyridylpolyenes (with 3 and 4 double bonds) give only ill-defined bands, which does not allow us to reach definitive conclusions on the decay law of the electronic interaction with distance. On the contrary, dipyridylthiophene and -furan present a better resolution of the intervalence transition, which is ascribed to a better coplanarity and rigidity.