Exploring transition state structures for intramolecular pathways by the artificial force induced reaction method

Finding all required transition state (TS) structures is an important but hard task in theoretical study of complex reaction mechanisms. In the present article, an efficient automated TS search method, artificial force induced reaction (AFIR), was extended to intramolecular reactions. The AFIR method has been developed for intermolecular associative pathways between two or more reactants. Although it has also been applied to intramolecular reactions by dividing molecules manually into fragments, the fragmentation scheme was not automated. In this work, we propose an automated fragmentation scheme. Using this fragmentation scheme and the AFIR method, a fully automated search algorithm for intramolecular pathways is introduced. This version for intramolecular reactions is called single‐component AFIR (SC‐AFIR), to distinguish it from multicomponent AFIR for intermolecular reactions. SC‐AFIR was tested with two reactions, the Claisen rearrangement and the first step of cobalt‐catalyzed hydroformylation, and successfully located all important pathways reported in the literature. © 2013 Wiley Periodicals, Inc. Artificial force induced reaction (AFIR), an efficient automated transition state search method, is extended for intramolecular reaction pathways. This is achieved by the introduction of a systematic fragmentation scheme of a molecule and an automated path search algorithm using the AFIR method. This version is called single‐component AFIR (SC‐AFIR) to distinguish it from the original multi‐component AFIR for intermolecular reactions. SC‐AFIR enables systematic examinations of complex reaction mechanisms involving intramolecular reactions.