ANALYSIS OF ALIPHATIC О±,П‰-DIOLS: CRYSTAL STRUCTURES, APPLICATION AND PROGRESS OF A. I. KITAIGORODSKY IDEAS
O. V. Grineva
Lomonosov State University, Moscow, Russia
Keywords: метод атом-атомных потенциалов, межмолекулярные взаимодействия, энергия кристалла, энергетическое координационное число, полиморфы, конформации, симметрия молекул в кристаллах, водородные связи, Кембриджский банк структурных данных, atom-atom potential method, intermolecular interactions, crystal energy, energy coordination number, polymorphs, conformations, molecular symmetry in crystals, hydrogen bonds, Cambridge Structural Database
Abstract
Based on the information from the Cambridge Structural Database, 28 crystalline homomolecular structures of a,w-diols are analyzed (five of them at two temperature). Two variants of violation of the A. I. Kitaigorodsky “centrosymmetric rule” are found: 1) approximately centrosymmetric molecules do not take positions in the centers of inversion, which are present in space groups; 2) the compound forms two polymorphs, one of which obeys the rule and in another the molecules have a substantially non-centrosymmetric conformation. It is shown that the molecular coordination number found from the calculation of distances combines the molecules whose interactions with the central molecule often have strongly different contributions to the crystal energy. The idea of the energy coordination number of molecules is introduced. It is found that in compounds with similar structures this parameter can have diverse values that are not an unambiguous consequence of the number of hydrogen bonds formed by molecules or the number of molecules thus bonded to the central one.
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