Localized lone pairs

Two of the worst outliers were N,N-dimethylformamide and N,N-dimethyl-acetamide. For both of these, solubility in water was greatly underestimated. This may illustrate a situation in which conformation does assume importance. In the gas phase structures used to compute the surface properties, the nitrogens are planar. There is reason to believe, however, that interaction with water molecules will cause the nitrogens to become pyramidal,48 since that produces more localized lone pairs that better attract water hydrogens. Thus, analysis involving planar nitrogens would not indicate the true strength of the interaction. 

Since phosphametallocenes still have a localized lone pair on phosphorus they can behave as two electron phosphorus donors towards other metallic centers. This possibility has been demonstrated for phosphacymantrenes phosphaferrocenes and 1,1 -diphosphaferrocenes with Fe(CO)4 as the acceptor group ... 

Finally, consider the two lone-pair MOs /i(0) and lz(0). These MOs are mainly localized on the oxygen atom and are equivalent to each other.They are directed away from the hydrogen atoms and project above and below the molecular (yz) plane (Fig. 15.8). The d- (yz) operation interchanges the lone-pair MOs. The angle between them is approximately 2 arctan (0.71/0.39) = 122°. The angle between localized lone-pair MOs calculated from a more accurate wave function is 114° W. von Niessen, Theor. Chim.Acta,29,29(W3). 

FIGURE 15.B Rough sketches of the localized lone-pair MOs of H2O. 

In reviewing the main contributions of the HIH paper, it will suffice to focus on one of the molecules, p-benzyne, considered in that study. /7-Benzyne has two half-occupied localized lone-pair orbitals, 0 and 02,... 

In an early study, Arduengo et al. conducted XPS and DFT studies on a model carbene, and on the analogous silylene and germylene [45]. While such studies showed a localized lone pair in the plane of the imidazolylidene ring, with an empty p orbital perpendicular to this, the electronic structures of the silylene and germylene analogs were quite different. The HOMOs in these compounds... 

A localized lone pair, by definition, is a lone pair that does not participate in resonance. In other words, the lone pair is not allylic to a it bond ... 

There are two lone pairs in the structure of nicotine. In general, localized lone pairs are much more reactive than delocalized lone pairs. With this information in mind, do you expect both lone pairs in nicotine to be reactive Justify your answer. 

A localized lone pair does not participate in resonance. 

Haworth projections 64 localized lone pair 83 partially condensed structures 50 resonance 67... 

Molecular Orbital Theory (Section 1.8) Delocalized and Localized Lone Pairs (Section 2.12)... 

Lone pair is localized Lone pair is delocalized... 

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