Orbital Resonances

Anti-bonding tt orbital, 293 Atomic orbital resonance, 295 16/3-Azido- 17a-iodoandrostanes, 24 16p-Azido-17a-iodo-5a-androstan-3 -ol acetate, 28... 

Y. Yano and S. Oae, 3d Orbital Resonance in the Bivalent Sulfur Atom, Mechanisms of Reactions of Sulfur Compounds, Vol. 4, Intra-Science, 1969, p. 167. 

The next-nearest-neighbor-orbital resonance integrals, /JI3, also remain unaffected by the pure twisting motion. We conclude that a pure twisting motion can therefore represent at best only a relatively small perturbation of the electronic structure of the polysilane chain, suitable for treatment by first-order perturbation theory. The perturbation is represented by changes in the resonance integrals between more distant hybrid orbitals, among which / 14 clearly is the most important. 

In the Landauer/Imry limit, the transport through the junction is due to elastic scattering. If the gap between the injection energy and the frontier orbital resonance is large, the Landauer/Buttiker contact time is very small, so that the charge is present on the molecule for a very short time. This means that its interaction with any vibration will be weak, because there just is not time to complete a full vibrational period before the charge has gone into the electrode sink. 

As pointed out above, neither methane nor its higher homologs (ethane, propane, hexane) can be effectively metalated. The introduction of a hetero-substituent changes this outset profoundly. Second-row and third-row elements (such as silicon, phosphorus and sulfur) will not be considered in this context as they are known to acidify hydrocarbons strongly due to d-orbital resonance (or polarization) effects. But also the first-row elements nitrogen, oxygen and fluorine can distinctly facilitate the deprotonation of paraffinic hydrocarbons. 

The sharp structures above 50 meV are the result of orbiting resonances from the deep attractive well of Vu. All particles can tunnel through the maximum in Vu. The amplitude for finding a particle inside the maximum will be resonantly enhanced if the kinetic energy matches the energy of a quasibound state of Vu. For energies much below the barrier height, the... 

Figure 45. Velocity dependence of total cross section for He (23S) +Ar. Solid curve is calculated from potential due to Brutschy et al. 100 points are measurements due to Trujillo.136 Orbiting resonances are indicated by (v,J) quantum numbers.

Here, the ylid form can be stabilized by enolate formation and by d-orbital resonance, which explains the moderate value of pK. The possibility of pseudo-base formation can be excluded (75) by comparison with u.v. spectra. Thus, polarography made it possible to detect and characterize stable ylid formation in solutions several years before these ylids were isolated. 

There is yet another rather unusual motivation of the present model, starting from the Hiickel MO, Hubbard or Parisier-Parr-Pople models. This is Zivkovic s so-called bond-orbital resonance-theoretic approximation [64] for solving these latter models. He makes a wavefunction Ansatz... 

Valence bond hybridization of orbitals, resonance, and sigma and pi bonds... 

As already pointed out, terms such as wave function, electron orbit, resonance, etc., with which we describe the formulations and results of wave mechanics, are borrowed from classical mechanics of matter in which concepts occur which, in certain respects at least, show a correspondence to the wave mechanical concepts in question. The same is the case with the electron spin. In Bohr s quantum theory, Uhlenbeck and Goudsmit s hypothesis meant the introduction of a fourth quantum number j, which can only take on the values +1/2 and —1/2- In wave mechanics it means that the total wave function, besides the orbital function, contains another factor, the spin function. This spin function can be represented by a or (3, whereby, for example, a describes the state j = +1/2 and P that with s = —1/2. The correspondence with the mechanical analogy, the top, from which the name spin has been borrowed, is appropriate in so far that the laevo and dextro rotatory character, or the pointing of the top in the + or — direction, can be connected with it. A magnetic moment and a... 

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