Ruthenium(II) Dichloride Complexes of Chiral, Tetradentate Aminosulfoxide Ligands: Stereoisomerism and Redox-Induced Linkage Isomerism

Ruthenium­(II) dichloride complexes of two chiral tetradentate
aminosulfoxide ligands, varying only in the N–N linker, were
synthesized. With each ligand, two major isomers formed, and these
were structurally assigned and characterized through a combination
of NMR and UV–vis spectroscopies, X-ray crystallography, and
density functional theory calculations. The cis-β
geometric isomer was formed by each ligand, whereas the trans and cis-α geometric isomers were significant
components for one ligand only. Cyclic voltammetry studies show that
only the cis-β isomers undergo linkage isomerism
upon oxidation to ruthenium­(III), whereas the trans and cis-α isomers show simple reversible
redox couples.