Some examples of electron topology studies

In this section we put aU of this into practice with some examples to demonstrate what we can learn from electron density topology studies, but also to show what some of its limitations are. T vo further examples can also be found in case histories 12.10 and 12.12, where the charge density studies are placed into a wider context together with results from other methods. Charge density studies on various chemical topics are reviewed in [49]. 

Electron density plots of NH3, Sip4 and the adduct H3N-American Institute of Physics. 

In order to give an impression of how characteristic these values are, compare them with the parameters of the dative B—N bonds in H3N BF3, H4N2 BH3 and H4N2-(BH3)2 listed in Table 10.4 [52]. These experimental values also provide estimated standard deviations (in parentheses). They show that we should expect some range in the values of Pbcp and - perhaps unexpectedly - the differences arc greater for the two BH3 adducts of hydrazine than between the adduct H4N2 BH3 with a hydridoborane unit and H3N BF3 containing a trifluoroborane unit [52]. 

2 Reactive surfaces, molecular recognition and crystal packing 

The concept of local charge accumulation and depletion, analyzed by the negative Laplacian of the electron density distribution, offers much more than a description of chemical bond properties and the location of non-bonded pairs of electrons, although this is a sound basis for the VSEPR model. Regions of local charge 

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