Utility of the Nudged Elastic Band Method in Identifying the Minimum Energy Path of an Elementary Organometallic Reaction Step

Abstract

The nudged elastic band (NEB) method has been used to re-examine the oxidative addition step in the classic rhodium-catalyzed hydroacylation reaction. Numerous additional intermediates were found on a pathway that is lower in energy than that originally reported. This study illustrates the potential limitations of the traditional approach to locating transition states in which a chemical-intuition-guided linear or quadratic synchronous transit is used to estimate the high point of the reaction trajectory. Utilization of that approach constrains the search so that the actual transition state and other possible intermediates and transition states may be missed.

DFT Mechanistic Investigation of an Enantioselective Tsuji–Trost Allylation Reaction

“…Routine density functional theory (DFT) computational tools are used along with the emerging nudged elastic band (NEB) methods for mapping the reaction minimum energy pathways, and the results provide a more detailed mechanism for this important reaction. We have previously demonstrated the utility of the NEB method in providing critical reaction energy path information in complex organometallic transformations, and the analysis reported herein reinforces this conclusion.…”

Nudged Elastic Band Method for Molecular Reactions Using Energy-Weighted Springs Combined with Eigenvector Following

“…Various interpolation methods , or relaxed surface scans (coordinate-driving) are often used to generate an initial configuration for a SP search . Another consideration for EF is that important features of the reaction path may be missed, such as possible intermediate states and other higher energy SPs that may lie between the reactant and product states . It is, therefore, advantageous to combine the double and single ended methods in a complementary manner, , where the double ended methods are used to find an approximate RP that identifies the important features of the MEP and provides a good initial guess configuration (and reaction coordinate) for the relevant, highest energy, first order SP characterizing the transition of interest.…”

Rhodium‐Catalyzed Enantioselective Intramolecular Hydroacylation of Trisubstituted Alkenes

“…The distinct differencei nr eactivity observed for substrates containing cycloalkenes of varied size, and the unexpected formation of cis-2b rather than trans-2b,l ed us to probe the mechanism of this transformation.W ec onducted DFT studies to model the reaction pathway for hydroacylation of both 1a and 1b (Figure 1; see the Supporting Information for detailed structures of I1-I5). [10][11] In theses tudies,c oordination of the substrate to the rhodium(I) catalystt hrough both the aldehyde oxygen and cycloalkene unit is highly exothermic (DH = À19.5 and À23.2 kcal mol À1 )a nd occurs to form I1.R eorientation of the substrate occurs to preorganize the aldehyde CÀHb ond for oxidative addition and generates I2.O xidative addition of the the rhodium(I) catalystt ot he aldehyde CÀHb ondl eads to I3,inw hichthe key acylrhodium(III) hydridei ss tabilized by the alkene unit of the cycloalkene (DH = À10.8 and À13.3 kcal mol À1 ). Migratory insertiong enerates intermediate I4 in which the acylrhodium(III) unit and the b-hydrogen reside on the same face of the cycloalkane in a cis orientation.R eorientation of the substrate occurs to form complex I5 and this species undergoes reductivee limination to generate the polycyclic ketone product as the trans diastereomer.…”