Effects of Substituted Triarylphosphine Ligands on Electron Transfer in [(<i>p</i>‑Cymene)Ru] Complexes

The consequences of electron transfer (ET) in ruthenium-arene catalysts supported by triarylphosphine ligands have not been fully elucidated in coordinating solvents, which are known to engender further transformations in analogous Ru species upon oxidation and may reveal new modes of reactivity in these compounds. Herein, we report electrochemical studies of (p-cymene)RuCl2(PArX3) complexes containing substituted triarylphosphines (PArX3) and the effects of the ligand substituents on ET processes. These complexes undergo ET at potentials that depend on the ligand substituents (X); in CH3CN, electrochemical oxidation generates new products whose formation and ET behavior also depend on these substituents. Based on evidence for loss of cymene in these transformations, the products of these reactions are formulated as the tris(nitrile) complexes (PArX3)RuCl2(NCCH3)3.