Intermolecular energy change

Considering only the interaction between HOMO of R and LVMO of S, elementary perturbation theory shows that the result of the orbital interaction is a repulsion of the levels, the occupied level becomes more stable, the unoccupied level less stable. The simplest Huckel-type formulation of PMO theory gives equations for the intermolecular perturbation energy change A that are quite simple in form, Eqs. 3—6 18,20,22,26-28) Q is a first-order Coulombic energy that can be calculated in terms of... 

In conclusion, the free energy change of an ET step is already a good indicator of the feasibility of the reaction. A highly endergonic reaction, with, say, AG° > 20 kcal mol-1, corresponds to a rather slow ET reaction that is not likely to compete with other reactions of polar nature. In the region where AG° lies between 20 and -A kcal mol-1, we need to apply the Marcus approach in order to get an approximate value of the ET rate constant, whereas at AG° < - A kcal mol-1 most intermolecular ET reactions appear to be diffusion controlled. 

The dissolution of a solute in a solvent has associated with it a free-energy change, AG = AH — TAS. The enthalpy change is the heat of solution (AHsoin), and the entropy change is the entropy of solution (ASsoin). Heats of solution can be either positive or negative, depending on the relative strengths of solvent-solvent, solute-solute, and solvent-solute intermolecular forces. Entropies of solution are usually positive because disorder increases when a pure solute dissolves in a pure solvent. 

Temperature Mean activation energy 1°C] Intermolecular energy change of the chain with the rotating ester Energy change of the surrounding... 

Intermolecular energy change Intramolecular energy change of other chains ... 

When two molecules approach each other, the initial interaction is dominated by (long-range) Coulomb forces. With decreasing intermolecular distance, the mutual polarization of the electronic structures of the compounds will increase, and at a reactive distance between the atomic centers A and B of the two molecules a partial delocalization of electronic charge between the two reaction sites takes place. Following a perturbational MO treatment as introduced by Klopman (1968), the energy change upon interaction between the atomic site A of a donor molecule (the nucleophile) and the atomic site B of an acceptor molecule (the electrophile), separated by the distance RAB, can be written as ... 

---