Synthesis and characterization of tridentate quinoline-based NCO ligands

Abstract

Over the last few decades, there has been growing interest in the coordination chemistry of N-heterocyclic carbenes (NHCs) and their use in catalysis, with pincer-type systems being particularly significant due to their ability to form chelates and undergo easy electronic and steric modifications. Our research group has developed Cu(I) complexes of pyridine-based NHC ligands, which we have explored for their potential in catalyzing C–C and C–X (X = O, N) cross-coupling reactions. Although high-valent {Cu-O2} species were identified as likely intermediates, we were unable to isolate a Cu(II) complex in the pincer CNC environment. In this study, we present the synthesis and characterization of novel tridentate NHC ligands containing phenol and quinoline wingtips, which are anticipated to stabilize higher oxidation states of transition metals such as Cu(II). Our current research endeavors center on developing various NCO ligands and examining their coordination chemistry.