Cis–Trans Interconversion in Ruthenium(II) Bipyridine Complexes

Most studies of ruthenium polypyridine complexes are devoted to their cis isomers. The fact that cis isomers are thermally more stable and thus easier to synthesize has prevented researchers from investigating the properties and applications of trans complexes. We present a study of thermal and photochemical cis–trans interconversion of the key complex [Ru­(bpy)2(PMe3)­(H2O)]2+ (bpy = 2,2′-bipyridine, PMe3 = trimethylphosphine), which results in specific synthetic applications of the trans species, potentially useful as a platform for designing highly efficient visible light activated caged compounds. We show, as a proof of concept, some examples of trans complexes bearing N-donor and P-donor ligands and their comparison with the cis isomers.