The Concept of Natural Ligand Nonbonded Repulsion. The Ethane Paradigm

  • Nicolaos Demetrios Epiotis
Part of the Lecture Notes in Chemistry book series (LNC, volume 34)


Nonbonded repulsion, commonly referred to as “steric effect”, is one of the priceless weapons of the conceptual arsenal of the chemist, especially the organic chemist. It is repeatedly invoked to rationalize why the most “crowded” arrangement of atomic nuclei is often the least stable one.1 The simplicity of the concept, an intuitively obvious one, has much to do with the popularity it enjoys. While excellent for a posteriori rationalization, the concept of nonbonded repulsion has no predictive value. For example, ethane is staggered but water is non-linear. If we did not know the actual physical facts, we would predict ethane to be staggered and water linear on the basis of “steric effects”. Furthermore, the concept of nonbonded repulsion is really an empirical one for it was originally developed by experimentalists in order to codify a subset (not a complete set) of experimental observations which indicated that “crowding” of nonbonded atoms is energetically unfavorable. Thus, the concept of nonbonded repulsion is both nonpredictive and nontheoretical (heuristic).


Spin Correlation Electron Delocalization Rotational Barrier Jahn Teller Single Electron Transfer 
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Copyright information

© Springer-Verlag Berlin Heidelberg 1983

Authors and Affiliations

  • Nicolaos Demetrios Epiotis
    • 1
  1. 1.Department of ChemistryUniversity of WashingtonSeattleUSA

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