Gillespie-Nyholm rule

The geometric structure of the covalent binary halides, whether neutral or complexed ions, can be explained on the basis of the Nyholm-Gillespie rules known as the Valence Shell Electron Pair Repulsion Model (VSEPR) theory the geometrical arrangements of the bonds around an atom in a species depends on the total number of electron pairs in the valence shell of the central atom, including both bonding... 

Transferability of ionic domains The Lewis S4)-Sidgwick-Powell 66)-Gillespie-Nyholm S6> rule... 

The Gillespie-Nyholm rules usually can also be applied to other polyanionic compounds with hypervalent atoms. As an example, some polytellurides are depicted in Fig. 13.6. The Te

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The Gillespie-Nyholm rules can be applied with the aid of this formulation. The occurrence of both kinds of building blocks in Li2Sb, chains and dumbbells, shows that in this case the Peierls distortion contributes only a minor stabilization and is partially overridden by other effects. The Peierls distortion cannot be suppressed that easily with lighter elements. 

It means, for example, that atomic data can only rarely be used as a substitute for molecular integrals since the atom-in-molecule orbitals are not the same as the separate atom orbitals — worse, they are no longer equivalent among themselves. An atomic self-repulsion integral (0j0, 0j0j) is different if 0j is the lone-pair hybrid of NH3 or the bond-pair hybrid as the Gillespie-Nyholm rules suggest. 

The most widely used qualitative model for the explanation of the shapes of molecules is the Valence Shell Electron Pair Repulsion (VSEPR) model of Gillespie and Nyholm (25). The orbital correlation diagrams of Walsh (26) are also used for simple systems for which the qualitative form of the MOs may be deduced from symmetry considerations. Attempts have been made to prove that these two approaches are equivalent (27). But this is impossible since Walsh s Rules refer explicitly to (and only have meaning within) the MO model while the VSEPR method does not refer to (is not confined by) any explicitly-stated model of molecular electronic structure. Thus, any proof that the two approaches are equivalent can only prove, at best, that the two are equivalent at the MO level i.e. that Walsh s Rules are contained in the VSEPR model. Of course, the transformation to localised orbitals of an MO determinant provides a convenient picture of VSEPR rules but the VSEPR method itself depends not on the independent-particle model but on the possibility of separating the total electronic structure of a molecule into more or less autonomous electron pairs which interact as separate entities (28). The localised MO description is merely the simplest such separation the general case is our Eq. (6)... 

The repulsion between charges is a general phenomenon for the forces determining the structure of compounds. Gillespie and Nyholm presented a very general rule for the influence of Coulomb interaction with the valence shell electron pair repulsion (VSEPR) theory. 

The rules are known in chemistry as the VSEPR rules, where VSEPR is the acronym of valence-shell electron-pair repulsion, and they were devised in 1957 by Gillespie and Nyholm, ] two young scientists—one English, Gillespie, and the other Australian, Nyholm—who were both students of Sir Christopher Ingold, one of the greatest British chemists in the post-Second World War era. 

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