Photoswitchable Arene Ruthenium Complexes Containing o‑Sulfonamide Azobenzene Ligands

A series of arene ruthenium complexes containing o-sulfonamide azobenzene ligands were synthesized and found to exhibit uncommon coordination pattern with an exocyclic NN bond. Upon irradiation, these complexes cleanly undergo E → Z photoisomerization followed by thermal Z → E isomerization (upon resting in the dark) whose rate is dependent on the solvent, the nature of the arene group, the sulfonamide moiety, and azobenzene substitution, as revealed by structure–property studies.