Congested molecules. Where is the steric repulsion? An analysis of the electron density by the method of interacting quantum atoms




The computed electron density of several congested saturated hydrocarbons and halogenated derivatives has been analyzed by the method of interacting quantum atoms (IQA). For all the molecules studied, the calculations show the existence of a bond path between the congested atoms and which, according to the Quantum Theory of Atoms in Molecules, indicates that there is a stabilizing interaction between these atoms. The bond path is found to exist up to interatomic distances well-beyond the sum of the van der Waals radii. The IQA results indicate that steric hindrance is not a repulsive force between the congested atoms but that is the result of an increase in the intra-atomic or self-energy of the congested atoms. This increase in self-energy is caused by the deformation of the atomic basin of the congested atoms. © 2013 Wiley Periodicals, Inc.