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Updated: Jul 3, 2025

Isolating Free Carbenes, their Mixed Dimers and Organic Radicals
Published on: April 19, 2019
Carbones (-C2--), carbenes (-C:-) and carbodications (-C2+-) on the magnetic criterion
Erich Kleinpeter1, Andreas Koch1
1Universität Potsdam, Institut für Chemie, Karl-Liebknecht-Str. 24-25, D-14476 Potsdam(Golm), Germany. ekleinp@uni-potsdam.de.
Abstract:
The spatial magnetic properties, particularly the through-space NMR shieldings (TSNMRSs, the anisotropy effect in 1H NMR spectroscopy) of carbenes, carbones and carbodication (carbo2+) compounds (with and without stabilization by NMe2 π-donation) and those of a number of carbo2+ analogues have been calculated using the GIAO perturbation method, employing the nucleus-independent chemical shift (NICS) concept, and visualized as iso-chemical-shielding surfaces (ICSS) of various sizes and directions. TSNMRSs prove the electronic structure of carbo2+ compounds to be completely different from those of carbenes and carbones, preferring both the π-electron distribution and the structure of allenes/cumulenes despite the central carbon atom being the most electrophilic centre.
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