Charge density of the biologically active molecule (2-oxo-1,3-benzoxazol-3(2H)-yl)acetic acid

What is it about?

X-ray diffraction probes the electron density of a sample. Electron density maxima from routine experiments can be associated with atom sites; derived geometric parameters can be very precise, but all atoms of an element are treated as spherical scattering centers of the same type, regardless of their electronic situation and bonding environment. In principle, this limitation can be overcome: Given sufficient crystal quality and suitable equipment, diffraction experiments of high resolution can be performed. These experiments are conducted at low temperature in order to minimize thermal motion and allow to access reflections at high resolution. Such high order reflections owe their intensity to the inner-most electron shells and essentially define the position of the core, whereas the outer valence electrons may be polarized, engage in covalent bonding or act as lone pairs. Thus, the experimental electron density becomes experimentally accessible and diffraction experiments can provide information concerning charge accumulation or depletion and the electron distribution along covalent bonds or in regions of short intermolecular contacts.

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