The Stereoelectronic Levels of Description

It is at the next, the stereoelectronic levels of description that molecules gain flesh and reality. Here, they are no longer viewed as geometrical abstractions, but as objects with a volume and a shape. At this level, the attributes/properties of bulk, surface and volume are modeled with van der Waals radii. When the temporal dimension is added to the picture, the molecules are no longer treated as purely spatial, but as spatiotemporal entities. In other words, it is the Ml stereodynamic structure of molecules that is described at this new level, to which correspond structural attributes or properties such as flexibility, conformational behavior and prototropic behavior. These depend heavily on the valence electrons, but it is at the next higher level of description that the latter enter explicitly into the picture. The stereoelectronic attributes are expressed as various measurable or computable electronic properties characteristic of the molecules themselves (e.g., electronic distribution), or affecting the space surrounding them (e.g., electrostatic field) [2].

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