EFFECTS OF RAPID INTRAMOLECULAR ELECTRON-TRANSFER ON VIBRATIONAL-SPECTRA

Single-electron reductions of linked triruthenium clusters of the gene ral type Ru-3-pyrazine-Ru-3 produced mixed valence systems showing spe ctroscopic characteristics of rapid intramolecular electron transfer. Reflectance infrared spectroelectrochemistry was used to characterize the vibrational spectra of mixed valence systems that contained one ca rbon monoxide ligand on each Ru-3 cluster. Infrared spectra in the CO stretching region showed two resolved, partially coalesced, and coales ced nu(CO) bands for clusters with rate constants for intramolecular e lectron transfer k(e) increasing from = 1 x 10(9) s(-1) up to 5 x 10(1 1) and 9 x 10(11) s(-1), respectively. These data provide a strong cor relation between rates of intramolecular electron transfer and infrare d spectral bandshape.