![]() ![]() ![]() A similar study has been reported by McAllister and Tidwell. They also analyzed the role of induction effect ( F) and resonance effect ( R) parameters of the substituent groups on charge distribution. studied isodesmic substituent stabilization energies in disubstituted ketenes relative to alkenes and correlated them with group electronegativities. The quantization of the induction and resonance effects is most often done by using Hammett's equations. It is common to distinguish between the inductive effect and the resonance effect which are described as σ- and π-electronegativities, respectively. Relatively few methods have been proposed for the evaluation of group electronegativity and most of them have been used to evaluate only small subsets of the chemically interesting groups of atoms. Despite computational advances and availability of large number of experimental data, not many theoretical studies have been reported for group electronegativity. The electronegativity associated with functional groups is therefore called group electronegativity or substituent electronegativity. In organic chemistry, electronegativity is associated more with different functional groups rather than with individual atoms. Most of the attempts to develop electronegativity scale considered electronegativity as an atomic property although from Pauli's original definition, electronegativity is the power or tendency of a group of atoms in a molecule to attract electrons to themselves. The factor 1/2 in Eq. (12.14.2) was introduced by Mulliken as he considered that χ as an arithmetic mean of I and A is an easily grasped concept. It, therefore, makes sense to define electronegativity as ( I + A). (12.14.4) or, for system X = for system Y ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |