Redox Isomeric Ferrocenyl Styrylruthenium Radical Cations with Diphenyl-Substituted β-Ketoenolato Ligands

We report on 18-valence-electron ferrocenyl vinylruthenium conjugates 4-Fc-C6H4-CH═CH-Ru(CO)Cl(PiPr3)2(PhR2acac) where PhR2acac denotes a diphenylacetylacetonato ligand with two 4-substituted (R = OMe, 2-OMe; R = H, 2-H; R = F, 2-F; R = CF3, 2-CF3) or perdeuterated (R = C6D5, 2-D) phenyl substituents. The complexes undergo two reversible one-electron oxidations whose potentials depend on the aryl substituents R. The one-electron oxidized forms of these complexes exist as two different isomers, which differ with respect to whether the electron loss has primarily occurred from the ferrocene or the styrylruthenium site. These isomers are clearly distinguished by characteristic features in their infrared, near-infrared, EPR, and Mosbauer spectra. Electron-withdrawing substituents R at the PhR2acac coligand increase the proportion of the ferrocenium-type species, whereas electron-donating ones have the opposite effect.