{"term":{"id":"01886","title":"eclipsing strain","longtitle":"IUPAC Gold Book - eclipsing strain","doi":"10.1351\/goldbook.E01886","code":"E01886","status":"current","synonym":"<em>synonyms<\/em>: bond opposition strain, Pitzer strain, torsional strain","definitions":[{"id":1,"text":"Intramolecular strain present due to nonbonded interactions between two eclipsed atoms or groups. It is, for example, one of the interactions responsible for the existence of a rotational barrier and hence restricted rotation about the $\\ce{C–C}$ bond in ethane. It has also been called Pitzer strain, torsional strain and bond opposition strain.","links":[{"term":"Intramolecular","url":"https:\/\/goldbook.iupac.org\/terms\/view\/I03130"},{"term":"eclipsed","url":"https:\/\/goldbook.iupac.org\/terms\/view\/E01884"},{"term":"nonbonded interactions","url":"https:\/\/goldbook.iupac.org\/terms\/view\/N04183"},{"term":"restricted rotation","url":"https:\/\/goldbook.iupac.org\/terms\/view\/F02520"},{"term":"rotational barrier","url":"https:\/\/goldbook.iupac.org\/terms\/view\/R05408"},{"term":"strain","url":"https:\/\/goldbook.iupac.org\/terms\/view\/S06037"}],"sources":["PAC, 1996, 68, 2193. 'Basic terminology of stereochemistry (IUPAC Recommendations 1996)' on page 2206 (https:\/\/doi.org\/10.1351\/pac199668122193)"]}],"altoutputs":{"html":"https:\/\/goldbook.iupac.org\/terms\/view\/E01886\/html","xml":"https:\/\/goldbook.iupac.org\/terms\/view\/E01886\/xml","plain":"https:\/\/goldbook.iupac.org\/terms\/view\/E01886\/plain"},"citation":"Citation: 'eclipsing strain' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. 10.1351\/goldbook.E01886","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.","collection":"If you are interested in licensing the Gold Book for commercial use, please contact the IUPAC Executive Director at executivedirector@iupac.org .","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.","accessed":"2026-06-28T12:09:36+00:00"}}