Geometry of an Isolated Dimer of Imidazole Characterised by Rotational Spectroscopy and Ab Initio Calculations

John C. Mullaney, Daniel P. Zaleski, David P. Tew, Nicholas R. Walker*, Anthony C. Legon

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

11 Citations (Scopus)

Abstract

An isolated, gas-phase dimer of imidazole is generated through laser vaporisation of a solid rod containing a 1:1 mixture of imidazole and copper in the presence of an argon buffer gas undergoing supersonic expansion. The complex is characterised through broadband rotational spectroscopy and is shown to have a twisted, hydrogen-bonded geometry. Calculations at the CCSD(T)(F12∗)/cc-pVDZ-F12 level of theory confirm this to be the lowest-energy conformer of the imidazole dimer. The distance between the respective centres of mass of the imidazole monomer subunits is determined to be 5.2751(1) Å, and the twist angle γ describing rotation of one monomer with respect to the other about a line connecting the centres of mass of the monomers is determined to be 87.9(4)°. Four out of six intermolecular parameters in the model geometry are precisely determined from the experimental rotational constants and are consistent with results calculated ab initio.

Original languageEnglish
Pages (from-to)1154-1158
Number of pages5
JournalChemPhysChem
Volume17
Issue number8
DOIs
Publication statusPublished - 18 Apr 2016

Keywords

  • ab initio calculations
  • dimerization
  • hydrogen bonds
  • nitrogen heterocycles
  • rotational spectroscopy

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