Effects of Substituted Triarylphosphine Ligands on Electron Transfer in [(p-cymene)Ru] Complexes

The consequences of electron transfer in ruthenium-arene catalysts supported by triarylphosphine ligands has 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 the electrochemical characteriza-tion of (p-cymene)RuCl2(PArX3) complexes containing substituted triarylphosphine ligands (PArX3) and investigate the ef-fects of the ligand substituents on ET processes. These complexes undergo ET at potentials that depend on the phosphine ligand substituents (X); in coordinating solvents, electrochemically-generated Ru(III) species are converted into new prod-ucts whose formation and ET behavior also show dependence on the nature of these substituents. Based on literature prece-dent and 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.