Characterization of Competing Halogen- and Hydrogen-Bonding Motifs in Simple Mixed Dimers of Hcn and Hx (X = F, Cl, Br, and I)

Author

Morgan A. Perkins
Gregory S. Tschumper, Missouri University of Science and TechnologyFollow

Abstract

This work performs the first systematic comparison of hydrogen- and halogen-bonded configurations of the HCN/HX mixed dimer, where X = F, Cl, Br, and I. Eleven different minima have been characterized for these four heterogeneous dimers near the CCSD(T) complete basis set (CBS) limit. For each complex, two different hydrogen-bonded minima were identified: the global minimum where HX acts as the hydrogen bond donor and a local minimum where HX acts as the hydrogen bond acceptor. A halogen-bonded local minimum was also identified for all but the fluorine mixed dimer. To the best of our knowledge, three of the minima are identified here for the first time. The hydrogen- and halogen-bonded local minima of each complex become more energetically competitive with the global minimum as the atomic radius of the halogen atom increases. CCSD(T) relative energies of the hydrogen-bonded local minima computed near the CBS limit decrease from 4.5 kcal mol-1 for HCN/HF to 2.9, 2.4, and 1.2 kcal mol-1 for X = Cl, Br, and I, respectively. Corresponding relative energies for the halogen-bonded local minima range from 4.0 kcal mol-1 for X = Cl to 2.7 kcal mol-1 for X = Br and to as little as 0.5 kcal mol-1 X = I. Harmonic vibrational frequency shifts reported here suggest that it may be feasible to differentiate between the various minima for X = Cl, Br, and I via spectroscopic analysis, as was the case for the HCN/HF dimer.

Recommended Citation

M. A. Perkins and G. S. Tschumper, "Characterization of Competing Halogen- and Hydrogen-Bonding Motifs in Simple Mixed Dimers of Hcn and Hx (X = F, Cl, Br, and I)," Journal of Physical Chemistry A, vol. 126, no. 23, pp. 3688 - 3695, American Chemical Society, Jun 2022.

The definitive version is available at https://doi.org/10.1021/acs.jpca.2c02041

Department(s)

Chemistry

Comments

National Science Foundation, Grant CHE-1664998

International Standard Serial Number (ISSN)

1520-5215; 1089-5639

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2024 American Chemical Society, All rights reserved.

Publication Date

16 Jun 2022

PubMed ID

35652358