When phosphorus and NHC (N-heterocyclic carbene) meet each other

Since the discovery of the first air stable NHC, this class of compounds has been intensively studied and applied in organometallic chemistry and homogeneous catalysis due to the stability brought to the metal centre. Alternatively, phosphorus based family ligands have already a very long history in these fields of chemistry. It was naturally obvious that the NHC and the phosphorus ligands had to be mixed for the best of organometallic chemistry and homogeneous catalysis. This perspective will highlight the new synthetic routes for NHC bearing a phosphorus moiety such as NHC-phosphenium salt, N-phosphorylated-imidazolium salt, 4-phosphino or 4,5-diphosphino-imidazolium salt and tethered phosphino-imidazolium salt. Then, the recent applications in organometallic chemistry and homogeneous catalysis will be presented.