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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.
The Journal of Physical Chemistry. A
|January 18, 2017
Summary
Researchers investigated tricyanomethane and its isomers, identifying dicyanoketenimine as a stable, related species. Water molecules facilitate their interconversion, offering new insights into HC4N3 chemistry.
Area of Science:
- Computational chemistry
- Theoretical organic chemistry
- Molecular spectroscopy
Background:
- The isolation of tricyanomethane (HC(CN)3) has spurred interest in related HC4N3 isomers.
- The existence and properties of other HC4N3 species remain largely unconfirmed.
Purpose of the Study:
- To computationally investigate the relative stabilities and spectroscopic features of tricyanomethane and its four isomers.
- To elucidate the rearrangement pathways and energy barriers between these HC4N3 species.
Main Methods:
- High-level single-reference (CCSD(T), CCSD(T)-F12) and multireference (MCSCF, MRPT2) quantum chemical methods were employed.
- Analysis of relative energies, spectroscopic parameters, and transition states for interconversion pathways.
Main Results:
- Tricyanomethane and dicyanoketenimine ((NC)2CCNH) were identified as the two most stable HC4N3 isomers, within 9 kcal/mol of each other.
- Distinct spectroscopic parameters can differentiate between these two stable isomers.
- A stepwise interconversion pathway was predicted, with the initial H migration to a CN carbon being the rate-limiting step.
- The presence of a water molecule significantly lowers the H migration barrier, enabling a more concerted interconversion.
Conclusions:
- The study provides a theoretical foundation for the existence and characterization of HC4N3 isomers.
- Computational data can guide experimental efforts in detecting and differentiating these elusive molecules.
- Water catalysis offers a potential mechanism for facile interconversion between key HC4N3 isomers.
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