Synthesis and Application of New Dipyrido-annulated N-Heterocyclic Carbene with Phosphorus Substituents

A new dipyrido-annulated N-heterocyclic carbene with phosphorus substituents at the 4 and 8 positions and the corresponding Rh(I) and Rh(111) complexes prepared from the carbene are reported. The X-ray structure of the Rh(I) complex 11 suggested the presence of strong interactions between the phosphorus atoms and Rh(I), in contrast to the previously reported sulfur-substituted system. The new carbene ligand shows promise as a useful carbene-centered pincer ligand with a fixed scaffold for other metal complexes.