Issue 10, 2024

Axial–equatorial equilibrium in substituted cyclohexanes: a DFT perspective on a small but complex problem

Abstract

In Chemistry, complexity is not necessarily associated to large systems, as illustrated by the textbook example of axial–equatorial equilibrium in mono-substituted cyclohexanes. The difficulty in modelling such a simple isomerization is related to the need for reproducing the delicate balance between two forces, with opposite effects, namely the attractive London dispersion and the repulsive steric interactions. Such balance is a stimulating challenge for density-functional approximations and it is systematically explored here by considering 20 mono-substituted cyclohexanes. In comparison to highly accurate CCSD(T) reference calculations, their axial–equatorial equilibrium is studied with a large set of 48 exchange–correlation approximations, spanning from semilocal to hybrid to more recent double hybrid functionals. This dataset, called SAV20 (as Steric A-values for 20 molecules), allows to highlight the difficulties encountered by common and more original DFT approaches, including those corrected for dispersion with empirical potentials, the 6-31G*-ACP model, and our cost-effective PBE-QIDH/DH-SVPD protocol, in modeling these challenging interactions. Interestingly, the performance of the approaches considered in this contribution on the SAV20 dataset does not correlate with that obtained with other more standard datasets, such as S66, IDISP or NC15, thus indicating that SAV20 covers physicochemical features not already considered in previous noncovalent interaction benchmarks.

Graphical abstract: Axial–equatorial equilibrium in substituted cyclohexanes: a DFT perspective on a small but complex problem

Supplementary files

Article information

Article type
Paper
Submitted
18 दिसम्बर 2023
Accepted
13 फरवरी 2024
First published
15 फरवरी 2024

Phys. Chem. Chem. Phys., 2024,26, 8094-8105

Axial–equatorial equilibrium in substituted cyclohexanes: a DFT perspective on a small but complex problem

H. Li, E. Brémond, J. C. Sancho-García, Á. J. Pérez-Jiménez, G. Scalmani, M. J. Frisch and C. Adamo, Phys. Chem. Chem. Phys., 2024, 26, 8094 DOI: 10.1039/D3CP06141H

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements