Force steric/exchange

At any rate, a minimum does represent a situation in which attractions and repulsions are balanced (Brehmer et al. 2000). The nomenclature of these intermolecular interactions is quite variegated and the terms are not always clearly defined or distinguished from one another. Some in common usage include van der Waals interactions, London forces, dipole-dipole interactions (and higher terms), dispersion forces, steric repulsion, hydrogen bonds, charge-transfer interactions (also called donor-acceptor interactions), electrostatic interactions, exchange repulsion forces, etc. 

The destabilization is caused by the exchange of electrons between the occupied orbitals through the orbital overlap. The force is then termed exchange repulsion or overlap repulsion. The exchange repulsion is a major cause of the steric repulsion. There are many occupied orbitals in the sterically crowded space. 

An iterative procedure using the solid film linear driving force model has been used with a steric mass action isotherm to model displacement chromatography on ion exchange materials and the procedure applied to the separation of horse and bovine cytochrome c using neomycin sulfate as the displacer.4 The solid film linear driving force model is a set of two differential equations imposing mass transfer limitations. 

Pseudotetrahedral complexes such as 17 (Scheme 1.17) were observed to possess a particularly rich substitution chemistry [37]. Complex 17 reacted cleanly with o-phenylenediammonium to give the covalent substitution product 18 shown in Scheme 1.17. This imine substitution was driven by the same pk, effect employed in the l-to-2 transformation of Scheme 1.2. In addition, 17 reacted cleanly with copper bis(biquinoline) complex 10 to give the coordinative substitution product 20. This ligand exchange appears to have been sterically driven the substitution of one of the encumbering di(imine) ligands for a less bulky biquinoline provided the driving force for this reaction [45],... 

The influence of steric factors was thoroughly studied in the reaction of Ln(btsa)3 with the alcohol tritox-H. While the reaction takes place with larger lanthanides like neodymium to yield the homoleptic alkoxide complexes (Eq. 18) [264], the analogous reaction does not work with smaller metals like yttrium and thulium (Eq. 19). However, variation of the reaction conditions to a stoichiometric solid reaction yielded a fully exchanged product along with an unexpected and unusual silylamine degradation [265] (Eq. 20). This degradation reaction seems to be sterically forced and points out N-Si bond disruptions and C-Si bond formations under mild conditions [114]. 

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