Heterobimetallic Iridium–Ruthenium Assemblies through an Ambidentate Triazole-Diylidene Ligand: Electrochemical Properties and Catalytic Behavior in a Cascade Reaction

The preparation in high yield of a (p-cymene)­RuII(triazolium-ylidene) complex allows the synthesis
of an heterobimetallic
IrIII–RuII complex with a triazole-diylidene
bridge. The same complex can also be prepared by starting from the
previously reported complex Cp*IrIII(triazolium-ylidene).
A full electrochemical study of the heterobimetallic complex has been
performed, and the results have been compared with those for the related
homobimetallic triazole-diylidene bridged complexes of ruthenium and
iridium, where a weak metal–metal interaction (class II, according
to the Robin and Day classification) has been detected. The Ir–Ru
complex and some other related (p-cymene)­Ru­(NHC)
complexes have been tested in a new tandem process, implying the chelation-assisted
arylation of arylpyridines with 1-(4-halophenyl)­ethanol. The arylation
is accompanied by the transformation of the alcohol into a ketone,
in the presence of acetone, through an Oppenauer oxidation process.