Microwave spectrum and structure of the 3,5-difluoropyridine⋯CO2 van der Waals complex

Christopher T. Dewberry, Ryan D. Cornelius, Rebecca B. Mackenzie, C. J. Smith, Michael A. Dvorak, Kenneth R. Leopold

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6 Scopus citations


The rotational spectrum of the weakly bound complex 3,5-difluoropyridine⋯CO2 has been observed using pulsed-nozzle Fourier transform microwave spectroscopy. Spectroscopic constants are reported for the parent and 13CO2 isotopologues. The data indicate a planar structure in which the nitrogen approaches the carbon of the CO2 with either a C2v or effectively C2v geometry in the ground vibrational state. The N⋯C van der Waals bond distance is 2.8245(16) Å and the oxygen⋯ortho-hydrogen distance is 3.091(2) Å. The N⋯C van der Waals bond length is 0.027(8) Å longer than that previously determined for pyridine–CO2, but is still considerably shorter than the 2.998 Å distance in HCN⋯CO2. M06-2X/6-311++G(3df,3pd) calculations place the binding energy of the complex at 4.3 kcal/mol (4.1 kcal/mol with counterpoise correction). The calculations further indicate that a secondary interaction between the ortho-hydrogens of the ring and the CO2 oxygens account for ∼50% of the total binding energy.

Original languageEnglish (US)
Pages (from-to)67-72
Number of pages6
JournalJournal of molecular spectroscopy
StatePublished - Oct 1 2016

Bibliographical note

Funding Information:
This work was supported by the National Science Foundation (Grant Nos. CHE-1266320 and CHE-1563324 ), the St. Cloud State University Office of Sponsored Programs , St. Cloud State University College of Science and Engineering , and by an NSF REU Research Fellowship awarded to R.D.C. through the University of Minnesota. We are grateful to Professor Steven Kass for helpful discussions.


  • Carbon dioxide complex
  • Difluoropyridine
  • Microwave
  • Weakly bound complex

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