Fifteen cyclic and acylic carbenes have been calculated with density functional theory at the BP86/def2-TZVPP level. The strength of the internal X→p(π) π-donation of heteroatoms and carbon which are bonded to the C(II) atom is estimated with the help of NBO calculations and with an energy decomposition analysis. The investigated molecules include N-heterocyclic carbenes (NHCs), the cyclic alky...

N-heterocyclic carbenes have been successfully established as versatile ligands in coordination chemistry, as powerful ancillary ligands in catalysis, as organocatalysts, and for an increasing number of other applications. In view of these applications the ability to vary the steric and electronic character of these ligands systematically, using simple modular synthetic routes, is a central the...

By reviewing the recent progress on the elucidation of the structure of gold carbenes and the definitions of metal carbenes and carbenoids, we recommend to use the term gold carbene to describe gold carbene-like intermediates, regardless of whether the carbene or carbocation extreme resonance dominates. Gold carbenes, because of the weak metal-to-carbene π-back-donation and their strongly elect...

Here we present a protocol for the synthesis of two distinct carbonyl-decorated carbenes. Both carbenes can be prepared using nearly identical procedures in multi-gram scale quantities. The goal of this manuscript is to clearly detail how to handle and prepare these unique carbenes such that a synthetic chemist of any skill level can work with them. The two carbenes described are a diamidocarbe...

A brief review is given of the structures of an important class of reactive intermediates, divalent carbon species (carbenes). The electronic properties of carbenes force an unusual electronic character upon these species that, in turn, leads to intriguing physical and chemical properties. Because of the fleeting nature of carbenes, which are extraordinarily reactive, direct investigation of th...

In regard to the worldwide interest in synthesis and application of stable carbenes, DFT calculations (B3LYP/6-311++G**//B3LYP/6-31+G* levels) are employed to reach at a series of phenyl carbenes. The singlet-triplet energy separations (ΔES-T), HOMO–LUMO energy gaps (ΔEHOMO-LUMO), as well as philicity indices (N and ω) and basicity of these carbenes are compared and contrasted with the synthesi...

N-heterocyclic carbenes are a class of persistent carbenes stabilized by adjacent heteroatoms that are part of a heterocycle. They play a central role in multiple enzymatic biosynthetic reactions that involve thiamine diphosphate. Inspired by this biocatalysis machinery, N-heterocyclic carbenes have emerged as one of the most versatile classes of organocatalysts for organic reactions. However, ...

Treatment of N-heterocyclic carbenes (as their free carbenes or generated in situ) with alkyl, aryl, acyl or tosyl azides afforded the respective substituted triazenes in excellent yields.

How to isolate small carbenes, previously reported from dimers instantaneously, and how split triaminoolefins into free carbenes.

The exclusive formation of the 1,5-cycloaddition product between azides and alkynes is taken advantage of in generating the first examples of abnormal carbenes from these precursors. This new route provides unprecedented post-functionalization possibilities for such abnormal carbenes.