Novel rhodium and iridium complexes coordinated to C3‑symmetric tris-NHC ligands based on a 1,3,5-triphenylbenzene core. Electronic and catalytic properties

摘要

A series of novel tris-azolium salt precursors based on 1,3,5-triphenylbenzene have been prepared. These salts exhibit fluorescenceemission in the 320−420 nm region. The coordination of these salts to[MCl(COD)]2 (M = Rh, Ir) was carried out in the presence of KHMDSand allowed the formation of the corresponding tris-NHC complexes of Rhand Ir in high yield. The electronic properties of the new complexes wereanalyzed by means of cyclic voltammetry and IR spectroscopy of the relatedcarbonylated species. The catalytic activity of the trirhodium complextoward the addition of arylboronic acids to cyclohexen-2-one has beenevaluated and compared to the activity shown by a related monometalliccomplex.