Electronegativity, and effects

The introduction of heteroatoms into cyclic systems produces significant variations in the molecular geometry that reflect the changes in covalent radii, relative electronegativity and effective hybridization. Consequently, there are changes in the bonding and the physico-chemical characteristics of these heterocyclic systems—particularly in small ring systems. 

Gasteiger, J. and Hutchings, M.G., Quantitative Models of Gas-Phase Proton Transfer Reactions Involving Alcohols, Ethers, and their Thio Analogs. Correlation Analyses Based on Residual Electronegativity and Effective Polarizability, J. Amer. Chem. Soc. 106, 6489, 1984. 

Batsanov SS (1975) System of electronegativities and effective atomic charges in crystaUine compounds. Russian J Inorg Chem 20 1437-1440... 

Batsanov SS (1971) Electronegativity and effective charges of atoms. Znanie, Moscow (in... 

Previous studies with a variety of datasets had shown the importance of charge distribution, of inductive effect), of r-electronegativity, resonance effect), and of effective polarizability, aeffi polarizability effect) for details on these methods see Section 7.1). All four of these descriptors on all three carbon atoms were calculated. However, in the final study, a reduced set of descriptors, shown in Table 3-4, was chosen that was obtained both by statistical methods and by chemical intuition. 

An extended set of physicochemical descriptors was used in this study, including, for example, partial atomic charge and effective polari2 ability of the protons, average of electronegativities of atoms two bonds away, or maximum, T-atomic charge of atoms two bonds away. 

Electronegativity The effect of electronegativity on acidity is evident m the following senes involving bonds between hydrogen and the second row elements C N O and F... 

Electronegativity and hybridization effects combine to make the carbon of a carbonyl group especially deshielded Normally the carbon of C=0 is the least shielded one m... 

Steric and inductive effects determine the rate of formation of the pentacovalent siUcon reaction complex. In alkaline hydrolysis, replacement of a hydrogen by alkyl groups, which have lower electronegativity and greater steric requirements, leads to slower hydrolysis rates. Replacement of alkyl groups with bulkier alkyl substituents has the same effect. Reaction rates decrease according to ... 

In general, the dissection of substituertt effects need not be limited to resonance and polar components, vdiich are of special prominence in reactions of aromatic compounds.. ny type of substituent interaction with a reaction center could be characterized by a substituent constant characteristic of the particular type of interaction and a reaction parameter indicating the sensitivity of the reaction series to that particular type of interactioa For example, it has been suggested that electronegativity and polarizability can be treated as substituent effects separate from polar and resonance effects. This gives rise to the equation... 

Indolmycin, biosynthesis of, 864 Inductive effect. 37, 562 alcohol acidity and. 604 carboxylic acid strength and. 758 electronegativity and, 37 electrophilic aromatic substitution and, 562... 

Optical electronegativity and nephelauxetic effect in oxide systems. J. A. Duffy, Struct. Bonding (Berlin), 1977, 32,148-166 (33). 

All the elements in a main group have in common a characteristic valence electron configuration. The electron configuration controls the valence of the element (the number of bonds that it can form) and affects its chemical and physical properties. Five atomic properties are principally responsible for the characteristic properties of each element atomic radius, ionization energy, electron affinity, electronegativity, and polarizability. All five properties are related to trends in the effective nuclear charge experienced by the valence electrons and their distance from the nucleus. 

Drillon M, Darriet J (1992) Progress in Polymetallic Exchange-Coupled Systems, some Examples in Inorganic Chemistry. 79 55-100 Duffy JA (1977) Optical Electronegativity and Nephelauxetic Effect in Oxide Systems. 32 147-166... 

Any covalent bond between atoms of different elements is polar to some extent, because each element has a different effective nuclear charge. Each element has a characteristic ability to attract bonding electrons. This ability is called electronegativity and is symbolized by the Greek letter chi. When two elements have different electronegativity values, a bond between their atoms is polar, and the greater the difference (A. the more polar the bond. 

Duffy, J.A. Optical Electronegativity and Nephelauxetic Effect in Oxide Systems. Vol. 32, pp. 147—166. 

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