Counterintuitive Chemistry: Carbene Stabilization of Zero-Oxidation State Main Group Species

Abstract

Carbenes have evolved from transient laboratory curiosities to a robust, diverse, and surprisingly impactful ligand class. A variety of different carbenes have significantly contributed to the development of low-oxidation state main group chemistry. This Perspective focuses upon advances in the chemistry of carbene complexes containing main group element cores in the formal oxidation state of zero, including their diverse synthetic strategies, unusual bonding and structural motifs, and utility in transition metal coordination chemistry and activation of small molecules.

N-Heterocyclic Carbenes Capped Metal Nanoparticles: An Overview of Their Catalytic Scope

“…Thus, the strength of the ligand–metal bonds and their steric environment play an essential role in stabilizing MNPs. Due to their strong electron-donating ability and tunable steric properties, NHCs are already established as powerful ligands for stabilizing several reactive species. , Hence, in recent years in the field of nanochemistry, NHCs have become a suitable choice of surface-stabilizing agent compared to the widely used long aliphatic chains of thiols (−SH) and amines (−NH 2 ). ,, In 2005, Finke and co-workers reported the first example of NHC on a metal surface (IrNPs), which paved the way for various NHC-stabilized MNPs. Several modifications of NHCs showcase excellent surface stabilization of MNPs .…”

Pyridine-, Pyridazine-, Pyrimidine-, and Pyrazine-Derived Carbenes as Ligands for Transition-Metal Complexes: Perspectives from DFT Calculations

“…During the last 30 years of the development of stable carbene chemistry, there has been a constant race to obtain N-heterocyclic carbenes (NHCs) with record-breaking electron-donating properties. The higher the donor properties of a carbene, the more opportunities it provides for stabilization of coordinatively unsaturated metal complexes, stabilization of charged species, and activation of non-reactive bonds during catalytic transformations. , Pyridinium and diazinium carbenes are very strong electron-donating ligands. Moreover, they provide a rigid back-bone along with tunable steric properties.…”

“…The higher the donor properties of a carbene, the more opportunities it provides for stabilization of coordinatively unsaturated metal complexes, stabilization of charged species, and activation of non-reactive bonds during catalytic transformations. 50,51 Pyridinium and diazinium carbenes are very strong electron-donating ligands. Moreover, they provide a rigid back-bone along with tunable steric properties.…”

New Insight into the Reactivity of S,S-Bis-ylide

“…Since the discovery of ylides in the 1920s [1,2], their chemistry has experienced important growth [3][4][5], and they have become very important synthetic tools [6][7][8][9]. Bisylides, which are the combination of two ylide functions on a single carbon atom, have attracted significant attention from many research groups [10][11][12][13][14][15][16]. Indeed, since the first synthesis of carbodiphosphoranes I by Ramirez in the 1960s [17], many models have been developed (Figure 1).…”

“…The main application of bis-ylides remains their use as ligands because of the peculiar environment of the central carbon atom. In particular, the presence of two lone pairs located on a single carbon atom [10][11][12][13][14][15][16] offers unique coordination modes for transition metals. Indeed, Stephen took advantage of the presence of the two lone pairs to stabilize certain transition metals, achieving high efficiency in hydrogenation reactions [31].…”