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The Six Isomers of the Cyclohexanol Dimer: A Delicate Test for Dispersion Models
Author(s) -
Juanes Marcos,
Usabiaga Imanol,
León Iker,
Evangelisti Luca,
Fernández José A.,
Lesarri Alberto
Publication year - 2020
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.202005063
Subject(s) - cyclohexanol , dimer , chemistry , computational chemistry , molecule , intermolecular force , density functional theory , dispersion (optics) , london dispersion force , van der waals force , organic chemistry , physics , catalysis , optics
The cyclohexanol homodimer acts as a delicate test model of the role of dispersion forces in intermolecular association. Whereas phenol produces a single dimer, the suppression of π interactions and the larger conformational flexibility in cyclohexanol results in multiple isomerism, with six competing dimers of the free molecule being observed in a supersonic jet expansion. Rotational spectroscopy reveals accurate structural data, specifically the formation of homo‐ and heterochiral diastereoisomers and the presence of both equatorial and axial forms in the dimers. Four dispersion‐corrected density‐functional molecular orbital calculations were tested against the experiment, with B3LYP‐D3(BJ) offering good structural reproducibility with an Alrich's triple‐ζ basis set. However, the prediction of the dimer energetics is largely model‐dependent, thus offering a testbed for the validation of dispersion‐corrected computational models.