The preparation of rhenium based octahedral clusters containing N-heterocyclic carbenes is described. These represent the first examples of [M6(μ3-Q)8](n+) or [M6(μ3-X)8](n+) clusters to contain a carbene ligand of any type (NHC, Fischer or Schrock). Surprisingly, the NHC ligands attenuate their luminescent properties.

N-Heterocyclic carbenes (NHCs) were generated in-situ from imidazolium and imidazolinium salts by deprotonation of C-2 hydrogen and were used as ligands in the copper-catalyzed addition of diethylzinc to N-sulfonylimines. The copper-NHC complexes were shown to possess an efficient ligand acceleration effect (LAE).

The syntheses of unsymmetrical N-heterocyclic carbenes (NHCs) that contain a single N-bound icosahedral carborane anion substituent are reported. Both anionic C-2 and doubly deprotonated dianionic C-2/C-5 NHC lithium complexes are isolated. The latter species is formed selectively, which reveals a surprising directing effect conveyed by icosahedral carborane anion substituents.

Functionalization of N-heterocyclic carbenes (NHCs) has an important influence on their stability, Lewis donor, and acceptor properties. In this study, we report on the selective functionalization of a four-membered N-heterocyclic bis-silylene (2,6-Ar2C6H3NSi:)2 (1) (Ar = 2,4,6-iPr3C6H2) with mono-oxygen sources N2O and Me3NO. Treatment of 1 with N2O results in the selective formation of mono-s...

Suzuki-Miyaura coupling reactions are promoted by Pd complexes ligated with C₂-symmetric multi-dentate N-heterocyclic carbenes derived in situ from Pd(OAc)₂ and imidazolium salts. Good to excellent yields were obtained for aryl bromides as substrates. Turnover numbers of up to 10⁵ could be achieved with 5 × 10⁻⁴ mol% of Pd(OAc)₂/1 × 10⁻³ mol% NHC precatalyst in 24 h.

Chiral N-heterocyclic carbenes were found to be efficient catalysts for the formal [2+2] cycloaddition reaction of alkyl(aryl)ketenes and nitroso compounds to give the corresponding 1,2-oxazetidin-3-ones in moderate to good yields with high enantioselectivities. Reductive ring-opening of the oxazetidinones give the corresponding α-hydroxy acid derivatives in good yields.

N-Heterocyclic carbenes bearing poly(ethylene glycol) chains of different lengths have been designed and employed as ligands in palladium-catalyzed coupling reactions. The catalyst system having longer chains was found to be highly efficient for Suzuki-Miyaura coupling and borylation reactions employing aryl chlorides under mild reaction conditions.

A series of C₂-symmetric chiral benzimidazolium salts, the precursor of N-heterocyclic carbene ligands, were designed and synthesized from 1,2-dibromobenzene. In situ prepared corresponding carbenes were tested in the asymmetric palladium-catalyzed intramolecular α-arylation of amides, affording chiral diarylmethanols with high yields and moderate enantioselectivities.

We report experimental and computational evidence that cationic N-heterocyclic carbene gold complexes with electron-rich cyclopropanes rearrange to produce Fischer gold carbene complexes in the gas phase, in analogy to long-known condensed-phase rearrangements of protonated cyclopropanes. Our results help to generalize the relationship between Lewis-acidic metal complexes of cyclopropanes, meta...

The organocatalytic behavior of N-heterocyclic carbenes in the aerobic oxidation of aromatic aldehydes to esters with boronic acids has been explored. This transition metal-free protocol allows access to a wide variety of aromatic esters in good to excellent yields under mild reaction conditions.