| A new series of mononuclear and binuclear ruthenium complexes were synthesized and their electrochemical and intervalence transfer (IT) properties studied. Techniques employed include cyclic voltammetry, coulometry, and near infrared spectroscopy.;Theoretical treatments given by S. B. Piepho, E. R. Krausz and P. N. Schatz (PKS) and by N. S. Hush allow for interpretation of experimental IT data. Calculations of electronic and vibronic coupling parameters, thermal electron transfer activation energies and rate constants, fundamental vibrational frequencies, and differences in potential between redox sites follow from these theories.;Series of binuclear ruthenium complexes of the form {(R(,2)-bpy)(,2)Ru(BiBzIm)Ru(R(,2)'-bpy)}('n+) (n = 2-4), symmetric (R = R' = H, methyl, methoxy or phenyl) and asymmetric (R = methyl, methoxy or phenyl; R' = H) have been prepared and studied. Near infrared spectral properties of the MV complexes appear to be consistent with the PKS and not the Hush theory. This is, in fact, reasonable as these complexes were determined to be fairly delocalized. The PKS theory is explicitly derived to treat delocalized systems whereas the Hush theory is strictly valid only in the strongly localized limit.;Series of mixed-ligand ruthenium complexes, {Ru(bpy)(,3-m)(R(,2)-bpy)(,m)}('n+) (m = 0-3; n = 1, 2; R = H, methyl, methoxy, phenyl, or ethyl carboxylate), were prepared and studied. Electrochemical studies suggest that the unpaired electron is the singly reduced (monocationic) form is localized on a single ligand at any given time for series with electron-withdrawing groups (ethyl carboxylate and phenyl). Such studies suggest the opposite behavior for series with electron-donating groups (methyl and methoxy). One possible explanation for this behavior is that the electron-donating groups lower the small thermal electron transfer barrier via a build up of electron density in the ligand (pi)* system.;From cyclic voltammetric measurements the conproportionation constants, substituent group effects, and relative potentials of redox sites are determined. Substituent group effects lend valuable information toward the extent of delocalization of electrons between redox sites within a series of mixed-valence (MV) compounds. Coulometry provides access to the MV complex through stoichiometric addition or subtraction of electrons. |
