The virtually unparalleled success of organometallic chemistry over the past 5 or 6 decades has been directly tied to the application of homogeneous, transition metal catalysis. The ability to, in a reproducible and modular manner, predict and control the selectivity or reactivity of a given reaction is one of the most powerful aspects of homogeneous catalysis. Within this context, the development of novel ligand scaffolds allows often exquisite control over the stereoelectronic nature of a metal center. Pincer ligands have emerged as a robust platform upon which numerous new complexes have been built and studied. Pincer ligands are usually tridentate and are capable of donating up to a total of six electrons to a central metal element; meridional coordination of the pincer to the metal center is often observed. Through coordination of a central donor atom and incorporation of two “donor” side arms, a tridentate chelate is formed. A strong, chemically and thermally robust complex forms from metal binding to both the central atom and the side-arm donors. Beyond their strong chelating ability and structural rigidity, perhaps the most valuable attribute of pincer ligands is their modular nature. Through modification of the central and side donors as well as the ligand backbone, it is possible to synthesize a huge number of ligands with a wide range of stereo-electronic properties. There are four general strategies presented in the literature for the metalation of pincer ligands: (1) direct cyclometalation, (2) oxidative addition, (3) transmetalation, and (4) transcyclometalation. Among them, direct cyclometalation is....
|Title of host publication
|Comprehensive Coordination Chemistry III
|Number of pages
|Published - Jul 21 2021