Pauling s principles

As we have pointed out many times previously, the columns of the standard tableaux functions are antisymmetrized, and the orbitals in a column may be replaced by any linear combination of them with no more than a change of an unimportant overall constant. In this case, consider a linear combination that has two hybrid orbitals that point directly at the H atoms in accord with Pauling s principle of maximum overlap. Using the parameter

[Pg.180]

A critical problem related to this is predicting the relative charge displacements which arise on coordination to a series of metal ions or of one metal ion in a series of different coordination environments. In this latter case there is a guide given by Nyholm 26) which is a corollary of Pauling s principle of electroneutrality. 

The structural unit for the simplest silicate, Si02, also known as silica, is the tetrahedron (see Figure 1.43). This is the result of applying Pauling s principles (Section... 

The concept of bond valence, which, as will be shown below, is the same as the bond flux derived in Chapter 2, grew out of attempts to refine Pauling s principles determining the structures of complex ionic crystals (Section 1.7). In this empirical evolution of Pauling s model, both the electrostatic and short-range components were developed simultaneously. Only later did it become apparent that it was also possible to derive the properties of the electrostatic component independently using the ionic theory. 

Pauling s principle of local electrical neutrality Charges are neutralized locally in crystals. Lewis s principle of zero formal charges Charges are neutralized locally in molecules. 

Developed in a period in which the reigning principle of structural chemistry was still Pauling s principle of maximiun overlap, the application of the NDO approximation enabled the reassessment of an assiunption as old as quantum chemistry itself, and furthermore showed that semiempirical methods could be applied to the quantitative prediction of the electronic stnictme and spectra of molecules of real interest to chemists. In fact, during the period 1961-1977, the papers of Parr and Pariser were among the five most cited publications of the 1950s in chemistry and physics (Pariser 1990, 322). Quantum chemistry was becoming an increasingly valuable tool for chemists—and computers played an indispensable part in this new trend. 

Pauling s landmark 1931 paper9 established the fundamental principles of the directed covalent bond ... 

Pattinson s lead white, 14 785 Pauli exclusion principle, silicon-based semiconductors and, 22 235 Pauling, Linus, 25 747-748 Pauling s rules, 22 453... 

Finally, according to Pauling s first rule one would expect lower tetrahedral defect and activation barrier energies in MO2 than in Lii/2M02 for both Co and Mn since the +4 cations have smaller radii than the +2 cations. Again, site-occupancy predictions based on Pauling s first rule run contrary to the results calculated from first principles. 

These principles are phrased in the language of the ionic model, but they provide a simpler and more explicit description of stable structures than that given by the ionic model s energy minimization principle. Among the important ideas captured by Pauling s rules are those of local charge neutrality, the definition of electrostatic bond strength, and the rule of parsimony which is closely... 

The course of modern organometallic chemistry has been greatly influenced by three simple generalizations the Dewar-Chatt-Duncanson synergic bonding model for metal-olefin complexes (40, 72) Pauling s electroneutrality principle (174), and the 18-electron or inert gas rule (202). In this section the impact of recent theoretical calculations on these important generalizations will be evaluated. 

Early in the last century, Paul Sabatier1 pointed out A most important property of an excellent catalyst is that it has an ability to bind many molecules but not too strongly . This Sabatier s principle is also the principle for how an excellent catalyst for electrochemical reactions works. In electrochemical terms, an active... 

A very promising recent approach to modeling angular geometries, the VAL-BOND model[30], is based on Pauling s 1931 paper1311 that established the fundamental principles of directed covalent bonds formed by hybridization. The VALBOND force field, which uses conventional terms for bond stretching, torsions, improper tor-... 

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