Acid-base concepts frontier orbitals

Lewis Acid-Base Concept and Frontier Orbitals 185... 

A number of concepts for general chemical reactivity exist, such as the principle of hard and soft acids and bases [17, 24], electronegativity [25-27] and frontier orbital theory [28-30]. 

One possible set of guidelines for acid-base interactions follows concepts from hard and soft acid-base theory to identify the hardness of the metal center as an acid and the hardness of the ligands, including important functional groups in the polymer, as bases. Frontier orbital energy differences between the highest occupied and lowest imoccupied molecular orbitals are small and perturbations in the electronic distribution occur rather easily, yielding covalent bonds for soft acid-base pairs. In... 

Li, Y, Evans, J. N. S. (1995). The fukui function a key concept linking frontier molecular orbital theory and the hard-soft-acid-base principle. J. Am. Chem. Soc. 117, 7756-7759. 

We attempt to extend the Hard-Soft Acid-Base (HSAB) principle for the reactions in solutions to interactions in solids. First we point out the important link between the absolute hardness of acid-and-base and the average energy gap. Then we discuss the electronic band structures of various solids, e.g., metals, semimetals, semiconductors and insulators. On the basis of energy gaps, we elaborate various consequences of the acid-base interactions in solids. The applications of HSAB principle and the frontier orbital concept to the solid adhesion and surface interactions between metals and polymers will be verified by experimental results reported in the literature. The new findings reported in this paper should be beneficial to those who are carrying out research in or processing thin-film microelectronic devices or thick-film multilayer structures. 

---