Abstract
N-heterocyclic carbenes (NHCs) are both relevant ligands in the fields of coordination and organometallic chemistry. During the last decade, several molecular systems combining porphyrins and NHC ligands were reported in the literature. Merging metalloporphyrins and NHC-metal complexes within unimolecular systems may lead to multimetallic species with new catalytic properties such as cooperative effects between inner and outer metal cations. Here, we present the synthesis and characterization of some molecular systems combining porphyrins and NHC-rhodium(I) complexes (see below). The catalytic properties of these complexes were investigated for the conjugated addition of phenylboronic acid to cyclohexen-2-one. We notably show the effect of the inner metal cations on the catalytic properties of the outer rhodium(I) complexes according to the structure of the ligand and the distance between the two metal centres. The results of this structure-function relationship study show a modulation of the catalytic properties of NHC-Rh(I) complexes by the porphyrin.