Term: metal to ligand charge transfer (MLCT) transition https://doi.org/10.1351/goldbook.M03868 Definition: An electronic transition of a metal complex that corresponds to excitation populating an electronic state in which considerable electron transfer from the metal to a ligand has occurred. Related Terms: 1) ligand to metal charge transfer transition (http://doi.org/10.1351/goldbook.L03520). 2) electronic state (http://doi.org/10.1351/goldbook.ET07026). 3) electron transfer (http://doi.org/10.1351/goldbook.E02011). Source: PAC, 1996, 68, 2223. 'Glossary of terms used in photochemistry (IUPAC Recommendations 1996)' on page 2254 (https://doi.org/10.1351/pac199668122223) Citation: 'metal to ligand charge transfer (MLCT) transition' 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.M03868 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.