Related Experiment Video
Updated: Mar 8, 2026

Isolating Free Carbenes, their Mixed Dimers and Organic Radicals
Published on: April 19, 2019
Cyanoform and Its Isomers. Relative Stabilities, Spectroscopic Features, and Rearrangements by Coupled Cluster and
Marek Szczepaniak1, Jerzy Moc1
1Faculty of Chemistry, Wroclaw University , F. Joliot-Curie 14, 50-383 Wroclaw, Poland.
Abstract:
Although an isolation of elusive tricyanomethane HC(CN)3 was recently reported, the existence of other HC4N3 species has yet to be confirmed. In this work, the relative stabilities, spectroscopic features, and rearrangements of tricyanomethane and its four isomers are examined using single- (CCSD(T), CCSD(T)-F12) and multireference (MCSCF, MRPT2) methods. Tricyanomethane and dicyanoketenimine (NC)2CCNH, which are found to be the two most stable HC4N3 isomers lying within 9 kcal/mol, can be discriminated by their spectroscopic parameters. The predicted stepwise interconversion path relating HC(CN)3 and (NC)2CCNH features the HC4N3 species comprising the C-C-N ring moiety, with the largest barrier being associated with the initial H migration to one of the CN carbons. Adding a water molecule reduces the H migration barrier strongly and makes it possible to interconvert tricyanomethane to dicyanoketenimine in a "concerted" way.
Related Concept Videos
Stability of Substituted Cyclohexanes
The two chair conformations of cyclohexanes undergo rapid interconversion at room temperature. Both forms have identical energies and stabilities, each comprising equal amounts of the equilibrium mixture. Replacing a hydrogen atom with a functional group makes the two conformations energetically non-equivalent.
For example, in...
Stereoisomerism of Cyclic Compounds
Disubstituted Cyclohexanes: cis-trans Isomerism
In cyclohexane, the substituents can occupy different positions generating distinct isomers....
Conformations of Cyclohexane
The chair form is the most stable and derives its name from its resemblance to the “easy chair.” In the chair conformation, two carbon atoms are arranged out-of-plane — one above and one below, minimizing the torsional strain. In the chair form, the bond angle is very close to the ideal...
Conformations of Cycloalkanes
¹H NMR of Conformationally Flexible Molecules: Temporal Resolution

