An ETS-NOCV-based computational strategies for the characterization of concerted transition states involving CO2

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  • Diego Sorbelli
  • Paola Belanzoni
  • Leonardo Belpassi
  • Lee, Jiwoong
  • Gianluca Ciancaleoni

Due to the presence of both a slightly acidic carbon and a slightly basic oxygen, carbon dioxide is often involved in concerted transition states (TSs) with two (or more) different molecular events interlaced in the same step. The possibility of isolating and quantitatively evaluating each molecular event would be important to characterize and understand the reaction mechanism in depth. This could be done, in principle, by measuring the relevant distances in the optimized TS, but often distances are not accurate enough, especially in the presence of many simultaneous processes. Here, we have applied the Extended Transition State-Natural Orbital for Chemical Valence-method (ETS-NOCV), also in combination with the Activation Strain Model (ASM) and Energy Decomposition Analysis (EDA), to separate and quantify these molecular events at the TS of both organometallic and organic reactions. For the former, we chose the decomposition of formic acid to CO2 by an iridium catalyst, and for the latter, a CO2-mediated transamidation and its chemical variations (hydro- and aminolysis of an ester) as case studies. We demonstrate that the one-to-one mapping between the “molecular events” and the ETS-NOCV components is maintained along the entire lowest energy path connecting reactants and products around the TS, thus enabling a detailed picture on the relative importance of each interacting component. The methodology proposed here provides valuable insights into the effect of different chemical substituents on the reaction mechanism and promises to be generally applicable for any concerted TSs.

Original languageEnglish
JournalJournal of Computational Chemistry
Issue number10
Pages (from-to)717–727
Number of pages11
Publication statusPublished - 2022

Bibliographical note

Publisher Copyright:
© 2022 The Authors. Journal of Computational Chemistry published by Wiley Periodicals LLC.

    Research areas

  • bond analysis, carbon dioxide, density functional theory, energy decomposition analysis, reaction mechanism

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