Deformations electron

Diels-Alder reactions, 4, 842 flash vapour phase pyrolysis, 4, 846 reactions with 6-dimethylaminofuKenov, 4, 844 reactions with JV,n-diphenylnitrone, 4, 841 reactions with mesitonitrile oxide, 4, 841 structure, 4, 715, 725 synthesis, 4, 725, 767-769, 930 theoretical methods, 4, 3 tricarbonyl iron complexes, 4, 847 dipole moments, 4, 716 n-directing effect, 4, 44 2,5-disubstituted synthesis, 4, 116-117 from l,3-dithiolylium-4-olates, 6, 826 electrocyclization, 4, 748-750 electron bombardment, 4, 739 electronic deformation, 4, 722-723 electronic structure, 4, 715 electrophilic substitution, 4, 43, 44, 717-719, 751 directing effects, 4, 752-753 fluorescence spectra, 4, 735-736 fluorinated derivatives, 4, 679 H NMR, 4, 731 Friedel-Crafts acylation, 4, 777 with fused six-membered heterocyclic rings, 4, 973-1036 fused small rings structure, 4, 720-721 gas phase UV spectrum, 4, 734 H NMR, 4, 7, 728-731, 939 solvent effects, 4, 730 substituent constants, 4, 731 halo... 

G. Will, Electron Deformation Density in Titanium Diboride Chemical Bonding in TiB2, Jour. Sol. St. Chem., 177, 628 (2004). 

The model of Jayanthi etal. overcomes the phenomenological force-constant models and thus avoids the large number of hypothetical force constants, sometimes used in these calculations. Jayanthi et al. calculate the charge density in each unit cell by an expansion over many-body interactions, which arise from the coupling of the electronic deformations to... 

Response temperature (operating temperature) may decrease in the foUowing order bond formation and cleavage —> molecular deformation lattice deformation —> electronic deformation such as SDW and charge-order melting. 

As A4> can amount to several volts, the electron deformation of the adsorbed molecules can be expected to influence their chemical behavior substantially. Therefore, when reactions are catalyzed via the intermediate formation of boundary layers on a catalyst, we may assume that the activation of the reacting molecules is frequently correlated to their polarization on the catalyst surface. There are two effects of polarization either it causes a strong but reversible adsorption, or the deformation of the electron shell of the adsorbed molecule is so thorough that the system—provided that it possesses sufficient activation energy— switches over irreversibly into a new quantized equilibrium position, forming a chemical bond (1) under liberation of energy. Intermediate states exist between these two extremes. 

Another way of characterizing the readiness of molecules to gain or lose electrons upon interaction is based on the concepts of molecular electronegativity and hardness (Berkowitz and Parr, 1988 Parr et al., 1978 Pearson, 1986 1991). The starting point is the consideration that both the extent and ease of electronic deformation will affect the reactivity of a chemical compound (cf. Schiiiirmann, 1998a). The electronegativity (EN) characterizes the tendency of atoms and molecules... 

Structural modifications brought about by an electric field can be of three kinds (a) orientation polarization, which can only take place for molecules having a permanent dipole moment, (b) atomic deformation polarization, (c) electronic deformation polarization. 

The electronic redistribution is akin in some ways to the electron flow associated with the formation of a covalent bond and might be thought of as a covalent contributor to the interaction. In any case, its energetic contribution can be defined simply enough as the difference in binding energy between the situation where electronic deformations of the monomers are not permitted (which yields the sum of electrostatic and exchange repulsion) and that where the electron cloud is free to adapt to the new situation of the complex. 

Fig. 11.1. Oxalic acid dihydrate. Electron deformation-density distribution a Multipole model density calculated in the plane of the oxalic acid molecule b Multipole model density calculated in the plane of the water molecule...

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