Jameson-Gutowsky equation

For the halogens, with the exception of fluorine, d-orbitals are in many cases suspected to take part in chemical bonding and may a priori be assumed to contribute to a. Jameson and Gutowsky have extended the Karplus-Pople treatment to also include d-orbitals [170]. The general expressions for in this more general case become rather lengthy and are not reproduced here. However, when only atomic orbitals centered on atom A are considered, the Jameson-Gutowsky equation for essentially takes the form... 

Letcher and Van Wazer applying LCAO theory first developed by Pople and Karplus and Das, have expressed the shielding (which was dominated by the magnitude of (7 ), in terms of localized bond parameters, e.g., ionic character, hybridization and double bonding. Using expressions for (7 obtained by Jameson and Gutowsky and taking account of both phosphorus p and d orbital occupation, the phosphorus chemical shift, <5 —was related to four parameters and/by equation (11)—... 

Jameson and Gutowsky used the independent electron molecular orbital and the valence bond approaches, including d orbitals explicitly. Their equations were applied extensively to shielding by Letcher and Van Wazer. ... 

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