Electrostatic Energy in Inorganic and Organic Salts Containing Octahedral SnCl62- Ion

Abstract

Hexachlorostannic acid is a precursor of derivatives of an ionic nature. The electrostatic part of the lattice energy in alkali metal salts and nitrogen organic base salts containing the sncls2-ion was determined by adopting the Ewald method. This approach requires knowledge of the complete or at least partial crystal structures of the compounds. In the case of incomplete structures the MNDO geometry optimization procedure was successfully applied to find the unknown positions of atoms, and thus permitted a wider representation of compounds to be considered. The crystal lattice energy calculations were carried out by taking from four different literature sources data regarding charge distribution in sncls2-. It was further assumed that the positive charge in cations was located either directly on certain atoms or distributed between all the atoms in these ions. These latter net atomic charges were evaluated by applying INDO and MNDO methods. The electrostatic energies derived compare well with published values of the crystal lattice energy; this implies that, in the case of the compounds examined, the main contribution to the cohesive forces is made by Coulombic interactions.

Lattice energy of organic ionic crystals and its importance in analysis of features, behaviour and reactivity of solid-state systems

“…The data presented in Table 2, as well as those for many other salts of mononitrogen organic bases [21][22][23][24], reveal that the Coulombic energy values evaluated theoretically compare quite well with the crystal lattice energies obtained from the thermochemical cycle. The method of evaluation of the charge distribution in the cation has only a minor effect on the Coulombic energy.…”

“…For the purpose of crystal lattice energy calculations, this information can also be obtained by employing quantum-chemistry methods. In several recent papers, we have done this for numerous nitrogen organic bases by using the INDO [25] and MNDO [26] methods [21][22][23][24]. These calculations revealed that the excess of negative charge usually occurs on N and sometimes C atoms.…”

“…In some cases, however, the in-formation is incomplete. One can then evaluate unknown positions of atoms by the careful employment of quantum-chemistry methods [21,24].…”

Comparison of the Ewald and Wolf methods for modeling electrostatic interactions in nanowires

“…The Madelung problem was solved with the Ewald summation [5], which through certain mathematical manipulations calculates the conditionally convergent O(r −1 ) Coulomb summation. It has been used to model proteins [6,7], salt compounds [8], semiconductors [9,10], and other materials. The Ewald summation, however, assumes periodicity of the modeled system and its application in physically non-periodic systems such as liquids, amorphous solids, and nanostructures is questionable [11].…”

Theoretical Studies on the Structure, Thermochemistry, Vibrational Spectroscopy, and Other Features of HfX62- (X = F, Cl, Br, I). Electrostatic Energy in Hexahalogenohafnates

“…This constitutes progress in comparison with our earlier studies, in which net atomic charges were obtained from the population analysis of semiempirical wave functions. [25][26][27] We believe that the approach adopted in this work constitutes a more reliable basis for examination of the interionic interactions in complex ionic substances.…”