Preston A. Chase

Metal-free reductions of N-heterocycles via Lewis acid catalyzed hydrogenation

N-Heterocycles form weak adducts with B(C(6)F(5))(3) that exist in equilibrium with the corresponding FLP; nonetheless, these heterocycles are reduced in the presence of a catalytic amount of the borane B(C(6)F(5))(3) and H(2).

Modern Organometallic Multidentate Ligand Design Strategies: The Birth of the Privileged “Pincer” Ligand Platform

The seemingly simple tridentate ligand design, one that is now known as the “pincer,” has gained increasing importance in metal–ligand chemistry and in other applications as diverse as organic synthesis, catalysis, and materials science. This chapter describes the historical context in which the pincer ligand platform developed and sketches how Shaw’s research played a crucial early role. The original chemistry, emerging in the late 1970s and early 1980s, is presented which details the synthesis and properties of the first examples of pincer-based organometallic complexes along with a selection of related species. Finally, a connection is made from this early start to the excellent and striving studies that currently are ongoing in pincer chemistry and its applications thereof.

Dendrimers incorporating metallopincer functionalities: synthesis and applications

The integration of metallopincer functionalities into dendrimers and other dendritic macromolecules is a mature but developing field. From the first reports on the uses of catalysis, the chemistry has blossomed to include some important contributions made to material chemistry and surface sciences as well as the continued relevance in the realm of catalyst recycling. One of the main advantages of employing pincer groups in these applications is the stability of metal-to-ligand organometallic bonds. Many metallodendrimers utilize dative interactions that anchor metal centers in dendrimer frameworks. In terms of their uses as recyclable catalysts, the dative-bonded complexes are generally more susceptible to metal leaching, a drawback that is most often avoided with metallopincers.

Nitrogen-based pincers: a versatile platform for organometallic chemistry

Pincer ligands form a simple design that has led to the development of a broad and diverse research portfolio of complexes that contain this motif. The typical designation of a pincer stems from the presence of two amines or other nitrogen-based donors that flank the central aryl or alkyl C−M bond. This chapter focuses on the transition metal complexes of pincer ligands, which contain a central aryl ring flanked by nitrogen-based donors––that is, NCN-type pincers. Compounds with this motif contain metals spanning the periodic table from titanium to mercury because of the ready availability of versatile organolithium synthons. Historically, pincer ligands are commonly associated with the transition metal organometallic chemistry. In addition to the well-developed organometallic chemistry, there is also a relatively rich and diverse variety of main group complexes that are studied in this chapter. In terms of impacts on organometallic and main group chemistry, complexes containing the NCN motif represent a large number of chemical “firsts.”