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Valence shell expansion

Atoms of these elements have empty J-orbitals in the valence shell. Another factor—possibly the main factor—in determining whether more atoms than allowed by the octet rule can bond to a central atom is the size of that atom. A P atom is big enough for as many as six Cl atoms to fit comfortably around it, and PC15 is a common laboratory chemical. An N atom, though, is too small, and NC15 is unknown. A compound that contains an atom with more atoms attached to it than is permitted by the octet rule is called a hypcrvalent compound. This name leaves open the question of whether the additional bonds are due to valence-shell expansion or simply to the size of the central atom. [Pg.199]

A hybridization scheme is adopted to match the electron arrangement of the molecule. Valence-shell expansion requires the use of d-orbitals. [Pg.235]

Jorgensen CK (1969) Valence-Shell Expansion Studied by Ultra-violet Spectroscopy. 6 94-... [Pg.248]

Lucken, E. A. C. Valence-Shell Expansion Studied by Radio-Frequency Spectroscopy. Vol. 6, pp. 1-29. [Pg.193]

However, there are some cases when an unpaired electron is localized not on the n, but on the o orbital of an anion-radical. Of course, in such a case, a simple molecular orbital consideration that is based on the n approach does not coincide with experimental data. Chlorobenzothiadiazole may serve as a representative example (Gul maliev et al. 1975). Although the thiadiazole ring is a weaker acceptor than the nitro group, the elimination of the chloride ion from the 5-chlorobenzothiadiazole anion-radical does not take place (Solodovnikov and Todres 1968). At the same time, the anion-radical of 7-chloroquinoline readily loses the chlorine anion (Fujinaga et al. 1968). Notably, 7-chloroquinoline is very close to 5-chlorobenzothiadiazole in the sense of structure and electrophilicity of the heterocycle. To explain the mentioned difference, calculations are needed to clearly take into account the o electron framework of the molecules compared. It would also be interesting to exploit the concept of an increased valency in the consideration of anion-radical electronic structures, especially of those anion-radicals that contain atoms (fragments) with available d orbitals. This concept is traditionally derived from valence-shell expansion through the use of d orbital, but it is also understandable in terms of simple (and cheaper for calculations) MO theory, without t(-orbital participation. For a comparative analysis refer the paper by ElSolhy et al. (2005). Solvation of intermediary states on the way to a final product should be involved in the calculations as well (Parker 1981). [Pg.8]

The immediate object of this review is the results of the application of radiofrequency spectroscopic methods to the valence-shell expansion problem but it is hoped that this will serve as an illustration of the more general one of their application to any problem in electronic structure. [Pg.2]

Valence-Shell Expansion Studied by Radio-Frequency Spectroscopy... [Pg.3]


See other pages where Valence shell expansion is mentioned: [Pg.12]    [Pg.502]    [Pg.503]    [Pg.502]    [Pg.503]    [Pg.35]    [Pg.13]    [Pg.156]    [Pg.356]    [Pg.261]    [Pg.253]    [Pg.2]    [Pg.9]    [Pg.10]   
See also in sourсe #XX -- [ Pg.170 ]

See also in sourсe #XX -- [ Pg.248 ]

See also in sourсe #XX -- [ Pg.16 ]




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