Term: halogen bond
https://doi.org/10.1351/goldbook.08173

Definition:
Association between a Lewis-acidic halogen atom in a molecular entity and a Lewis-basic region in another, or the same, molecular entity, which acts as an electron-pair donor, such that the balance of forces of attraction and repulsion results in net stabilization.

Notes:
1) Typical halogen-bond donors are \(\ce{I2}\), \(\ce{Br2}\), \(\ce{ICN}\), and \(\ce{IC#CH}\).
2) This is analogous to a hydrogen bond, in which the \(\ce{H}\) is the acidic atom.
3) The interaction provides a stabilization of a few \(\pu{kJ mol-1}\).

Source: PAC, 2022, 94, 353. 'Glossary of terms used in physical organic chemistry (IUPAC Recommendations 2021)' on page 427 (https://doi.org/10.1515/pac-2018-1010)

Citation: 'halogen bond' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.08173

License: The IUPAC Gold Book is licensed under Creative Commons Attribution-ShareAlike CC BY-SA 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) for individual terms.

Disclaimer: The International Union of Pure and Applied Chemistry (IUPAC) is continuously reviewing and, where needed, updating terms in the Compendium of Chemical Terminology (the IUPAC Gold Book). Users of these terms are encouraged to include the version of a term with its use and to check regularly for updates to term definitions that you are using.