BIFUNCTIONAL N-HETEROCYCLIC CARBENE-BASED PINCER LIGANDS AND THEIR COMPLEXES

Abstract

A series of Bifunctional N-heterocyclic carbene-based pincer ligands and their Ru and Rh complexes were synthesized and characterized. The ligand structure includes a central pyridine, NHC, and amino donor groups on side arms, providing tridentate coordination. The carbene side contains various substituents like Me, iPr, tBu, Ph for different sterics and electronic properties, and amino donor groups are isopropylamine and aniline. These ligands were used to obtain Ru and Rh complexes. As the metalation strategy was used, the transmetalation method, ligands were deprotonated with Ag2O to form an Ag complex, which was further treated with Ru and Rh precursors to form metal complexes. For the immobilization strategy, ligands functionalized with an alkoxysilane group (Si(OR)3) were also synthesized. These functional groups allow the covalent bonding of complexes on silica support (e.g., SiO2), creating stable heterogeneous catalysts. Further research will provide immobilization and study of the catalytic properties of these systems.