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Updated: Apr 21, 2026

Isolating Free Carbenes, their Mixed Dimers and Organic Radicals
Published on: April 19, 2019
Tuning the electronic and ligand properties of remote carbenes: a theoretical study
Bitupon Borthakur1, Taskia Rahman, Ashwini K Phukan
1Department of Chemical Sciences, Tezpur University , Napaam 784028, Assam, India.
Abstract:
The effect of annulation and carbonylation on the electronic and ligating properties of remote N-heterocyclic carbenes (rNHCs) has been studied quantum-chemically. The thermodynamic stability of these complexes has been assessed on the basis of their hydrogenation and stabilization energies, while HOMO-LUMO gaps are used to measure the kinetic stabilities. Annulated/carbonylated rNHCs are found to be weaker σ donors but better π acceptors compared with the parent rNHCs. The reactivity of these rNHCs has been studied by evaluating their nucleophilicity and electrophilicity indices. The nucleophilicity values are in good agreement with the σ basicities of all of the rNHCs. The (31)P NMR chemical shifts of the corresponding rNHC-phosphinidene adducts have been calculated and found to correlate well with the π acidities of these rNHCs.
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