Effects of Rapid Intramolecular Electron Transfer on Vibrational Spectra

Abstract
Single-electron reductions of linked triruthenium clusters of the general type Ru3-pyrazine-Ru3 produced mixed valence systems showing spectroscopic characteristics of rapid intramolecular electron transfer. Reflectance infrared spectroelectrochemistry was used to characterize the vibrational spectra of mixed valence systems that contained one carbon monoxide ligand on each Ru3 cluster. Infrared spectra in the CO stretching region showed two resolved, partially coalesced, and coalesced ν(CO) bands for clusters with rate constants for intramolecular electron transfer k e increasing from = 1 × 109 s 1 up to 5 × 1011 and 9 × 1011s 1, respectively. These data provide a strong correlation between rates of intramolecular electron transfer and infrared spectral bandshape.