COORDINATION CHEMISTRY OF N-HETEROCYCLIC CARBENES AND CYCLIC ALKYL AMINO CARBENES WITH TRANSITION METALS

Abstract

N-heterocyclic carbenes (NHC) and cyclic alkyl amino carbenes (cAACs) are state-of-the-art ligands in organometallic chemistry. They have been widely used as supporting ligands for transition metals to obtain complexes with diverse and interesting structural or catalytic properties. Palladium and nickel complexes of simple alkyl-tethered cis-chelating homo- and hetero-dicarbene ligands have been synthesized and characterized. DiNHC pro-ligands with NNN pincer functionalized tether have been designed, and the gold, palladium and cobalt coordination chemistry of the resulting potential pentadentate ligands have been explored. Catalytic activities of the mono- and di-palladium complexes with functionalized and non-functionalized diNHCs in direct C–H arylation of thiophenes with aryl and biaryl halides were investigated. Venturing beyond NHCs, the coordination chemistry of cAACs with molybdenum, nickel and palladium using unique cAAC∙HMDS adducts as ligand precursors was explored. Finally, the catalytic activities in olefin epoxidation reactions of the synthesized molybdenum complexes were studied.