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Intramolecular Noncovalent Carbon Bonding Interaction Stabilizes the cis Conformation in Acylhydrazones
Muhammad Moazzam Naseer1, Majid Hussain1, Antonio Bauzá2
1Department of Chemistry, Quaid-i-Azam University, Islamabad, 45320, Pakistan.
Chempluschem
|January 18, 2020
Summary
Noncovalent carbon bonding, a type of σ-hole interaction, stabilizes the cis conformation of amide groups in acylhydrazones. This interaction involves electron donation, contributing to molecular stability.
Area of Science:
- Chemical bonding
- Organic chemistry
- Computational chemistry
Background:
- Noncovalent carbon bonding is a recently identified σ-hole interaction.
- Previously considered weak and structure-dependent, its role in molecular stabilization is under investigation.
Purpose of the Study:
- To investigate the role of noncovalent carbon bonding in the intramolecular stabilization of the cis conformation of the amide moiety in acylhydrazones.
Main Methods:
- Computational analysis was employed to study the electronic interactions.
- The study focused on the electron donation from the nitrogen lone pair to the antibonding C-N orbital.
Main Results:
- A specific interaction, lone pair on nitrogen to antibonding C-N orbital [LP(N)→BD*(C-N)], was identified.
- A stabilization energy of E(2) = 1.2 kcal mol⁻¹ was calculated for this interaction.
Conclusions:
- Noncovalent carbon bonding plays a significant role in stabilizing the cis conformation of acylhydrazone amides.
- This interaction provides a quantifiable stabilization energy, challenging previous assumptions about its weakness.
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