HSAB and Molecular Orbital Theory

I Frontier molecular orbital (FMO) theory (sec. 11.2) correlates molecular orbital energies and orbital coeffi- 

Chapter 2. Acids, Bases, Functional Group Exchanges 

Reprinted with permission from Pearson, R.G. J. Chem. Ed., 198 7, 64, 561. Copyright 1987 American Chemical Society. 

These principles finally allowed Pearson to define hardness (t ) as follows a hard molecule resists changes in its electron charge cloud, both the total amount of charge and the charge distribution in space. A soft molecule has an easily changed electron distribution. 

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