06471 IUPAC Gold Book - transition structure 10.1351/goldbook.T06471 T06471 current 1 A saddle point on a potential-energy surface. It has one negative force constant in the harmonic force constant matrix. activated complex https://goldbook.iupac.org/terms/view/A00092 potential-energy surface https://goldbook.iupac.org/terms/view/P04780 saddle point https://goldbook.iupac.org/terms/view/C01145 transition state https://goldbook.iupac.org/terms/view/T06468 PAC, 1994, 66, 1077. 'Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)' on page 1174 (https://doi.org/10.1351/pac199466051077) https://goldbook.iupac.org/terms/view/T06471/html https://goldbook.iupac.org/terms/view/T06471/json https://goldbook.iupac.org/terms/view/T06471/plain Citation: 'transition structure' 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.T06471 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. If you are interested in licensing the Gold Book for commercial use, please contact the IUPAC Executive Director at executivedirector@iupac.org . 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. 2026-05-10T20:41:28+00:00