energia: Anthony J. Arduengo

Evidence: 100 • authority: 72

Anthony Joseph Arduengo III is Professor of the Practice at the Georgia Institute of Technology, Saxon Professor Emeritus of Chemistry at the University of Alabama, adjunct professor at the Institute for Inorganic Chemistry of Braunschweig University of Technology in Germany, and co-founder of the StanCE coalition for sustainable chemistry based on woody biomass (Xylochemistry). He is notable for his work on chemical compounds with unusual valency, especially in the field of stable carbene research.

Evidence: 48 • authority: 92

The crystalline radical anion salt of a free N-heterocyclic carbene.. Radical ions of free N-heterocyclic carbenes (NHCs) have remained short-lived, mostly elusive, intermediates so far. We probed the square schemes for proton-coupled electron transfers of representative redox-active free NHCs. We found that NHC radical anions NHC˙ - and/or the conjugated acid NHC·H˙ could be persistent. In the case of a benzoquinone-based NHC, both radical forms were isolated as stable crystalline compounds, characterized, including by single-crystal X-ray diffraction studies, and were engaged in the straightforward divergent syntheses of NHC-based radicals.. Authors: Smits P, Pecaut J, Philouze C, Fortage…

Evidence: — • authority: 72

In coordination chemistry, a transition metal NHC complex is a metal complex containing one or more N-heterocyclic carbene ligands. Such compounds are the subject of much research, in part because of prospective applications in homogeneous catalysis. One such success is the second generation Grubbs catalyst. Historically, N-heterocyclic carbenes were thought to mimic properties of tertiary phosphines. Many steric and electronic differences exist between the two ligands. Compared to phosphine ligands, NHC ligands' cone angle is more complex. The imidazole ring of the NHC ligand is angled away from the metal center, yet the substituents at the 1,3 positions of the imidazole ring are angled to…

Evidence: — • authority: 72

A persistent carbene (also known as stable carbene) is an organic molecule whose natural resonance structure has a carbon atom with incomplete octet (a carbene), but does not exhibit the tremendous instability typically associated with such moieties. The best-known examples and by far largest subgroup are the N-heterocyclic carbenes (NHC) (sometimes called Arduengo carbenes), in which nitrogen atoms flank the formal carbene. Modern theoretical analysis suggests that the term "persistent carbene" is in fact a misnomer. Persistent carbenes do not in fact have a carbene electronic structure in their ground state, but instead an ylide stabilized by aromatic resonance or steric shielding. Acid c…