Interatomic distances organic crystals

Most of the differences between inorgcmic, organic and protein crystals lies in the fact that ionic forces (found mostly in inorganic structures) depend upon interatomic distances but not on angle. In contrast, covalent bonds (such as those which predominate in organic and protein... 

Mpst of the structural information about complex gas molecules has been obtained by the electron-diffraction method. Values of interatomic distances and bond angles determined by this method before 1950 are summarized in a review article by P. W. Allen and L. E. Sutton, Acta Cryst. 3, 46 (1950). ValueB of interatomic distances and bond angles for organic molecules determined by both x-ray diffraction of crystals and electron diffraction of gas molecules are summarized in a 90-page table in G. W. Wheland s book Resonance in Organic Chemistry, John Wiley and Sons, New York, 1955, and by L. E. Sutton in Tables of Interatomic Distances and Configurations in Molecules and Ions, Chemical Society, London, 1958. (Later references to the latter book will be to Sutton Interatomic Distances.)... 

Organic Chemistry, John Wiley and Sons, New York, 1955, and Sutton, Interatomic Distances. Most of the values for crystals are from Strukturbcrichl, vols. I to VII (1913 to 1939), and Structure Reports, vol. 8 and later volumes. A useful compilation is R. W. G. Wyckoff, Crystal Structures, Interscience Publishers, New York, 1948 on. 

In the development of the set of intermolecular potentials for the nitramine crystals Sorescu, Rice, and Thompson [112-115] have considered as the starting point the general principles of atom-atom potentials, proven to be successful in modeling a large number of organic crystals [120,123]. Particularly, it was assumed that intermolecular interactions can be separated into dispersive-repulsive interactions of van der Waals and electrostatic interactions. An additional simplification has been made by assuming that the intermolecular interactions depend only on the interatomic distances and that the same type of van der Waals potential parameters can be used for the same type of atoms, independent of their valence state. The non-electric interactions between molecules have been represented by Buckingham exp-6 functions,... 

The Patterson function is a map that indicates all the possible relationships (vectors) between atoms in a crystal structure. It was introduced by A. Lindo Patterson " in 1934, inspired by earlier work on radial distribution functions in liquids and powders. In crystals the directionality as well as the lengths of vectors between atoms (atomic distances) can be deduced. By contrast, in liquids and powders the geometric information that can be obtained is limited to interatomic distances, because in these the molecules are randomly oriented. While the use of the Patterson function revolutionized the determination of crystal structures of small molecules in the 1930s to 1950s, direct methods are now the most widely used methods for obtaining structures of small organic molecules. The Patterson function, however, continues to play an essential part in the determination of crystal structures of inorganic compounds and macromolecules. It is also very useful when the structure of a small molecule proves difficult to solve by direct methods. 

Landolt-Bomstein, New Series, Vols. IIF5, ni/6, III/7, III/8, III/IO and III/14 (crystal stme-tures) O. Kennard, D. G. Watson, Eds. "Interatomic Distances 1960-65 Organic and Or-ganometallic Crystal Stmetures". Vol. A 1,1972, and subsequent volumes. 

O. Kennard et al. Interatomic Distances, 1960-1965. Organic and Organometallic Crystal Structures, Crystallographic Data Centre. Cambridge 1972. 

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