Intermolecular Covalent Interactions: A Unified Framework for Pnictogen-, Chalcogen-, Halogen-, and Hydrogen Bonds

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  • Presentation type: Apresentação Oral Assíncrona /Asynchronous Oral Communications
  • Track: Density Functional Theory
  • Keywords: Intermolecular Interactions; Bond theory; Density functional calculations;

Authors:

  • 1 Department of Theoretical Chemistry / Amsterdam Institute for Molecular and Life Sciences / Vrije Universiteit Amsterdam
  • 2 Universidade Federal de Lavras
  • 3 Department of Theoretical Chemistry / Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale Modeling (ACMM) / Vrije Universiteit Amsterdam

Intermolecular Covalent Interactions: A Unified Framework for Pnictogen-, Chalcogen-, Halogen-, and Hydrogen Bonds

Lucas de Azevedo Santos

Department of Theoretical Chemistry / Amsterdam Institute for Molecular and Life Sciences / Vrije Universiteit Amsterdam

Abstract

Intermolecular interactions are often referred to as non-covalent interactions. PnB, ChB, XB, and HB are significantly covalent in nature based on our quantitative KS-MO theory.
We challenge the commonly accepted, and purely electrostatic, sigma-hole model.
This model treats bond donors as a 2D surface with electrostatic potential.
Also, the bond acceptor is a point charge, which is far from the physical reality. "Non-Covalent Interaction" should be, thus, replaced by "Intermolecular Covalent Interaction".

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Author

Lucas de Azevedo Santos

Hi Sara, thank you!


Our analyses are completely based on quantitative KS-MO theory in combination with canonical energy decomposition analysis. Then, we establish causal relationships between the phenomena we observe and physically meaningful terms. On the other hand, topological analyses of the electron density provide indicators used to trace empirical correlations, lacking a consistent understanding of good or bad correlations. 

For instance, covalency, which comprises the electron-pair bonding or donor-acceptor orbital interactions, is well defined in our method by the relaxation of the anti symmetrized product wavefunction between two fragments. That is, how much is the orbital stabilizations due to the interaction between occupied and empty orbitals. The gradients of the electron density between chemical bonds do not necessarily translate these effects, especially for not considering orbital interactions. As such, it provides only a qualitative, instead of quantitative, picture of intermolecular interactions. In my opinion, it turns out to be unnecessary and just makes the argumentation weaker. 

 

Author

Lucas de Azevedo Santos

Oi Vinícius, muito obrigado! De fato, para interações fracas e/ou a longas distâncias, o modelo sigma-hole acidentalmente funciona. Como ele exatamente trata as interações como se fossem entre cargas pontuais, essa abordagem para campos de força, ou incorporar a polarizabilidade em métodos semi-empíricos, também irá funcionar. Entretanto, imagino que haveriam problemas em lidar com interações "Anti-electrostatic" (angew. chem. int. ed. 2020, 59, 11150). Quem sabe modificações no Lennard-Jones potential ajudariam nesse sentido, né?

Vinícius Bonatto

Entendi Lucas, obrigado pelo comentário. Bem observado, para este caso poderiam haver problemas.