ABSTRACT
Density functional theory calculations were carried out to investigate the electronic structures of Keggin-typed [XMo12O40]n- and [XW12O40]n- anions with different heteroatoms (X = Zn2+, B3+, Al3+, Ga3+, Si4+, Ge4+, P5+, As5+, and S6+). The influence of solvent on redox properties of heteropolyanions was discussed. For [XW12O40]n- systems two linear correlation: first, between the experimental redox potential and energies of LUMO orbital; and second, between the experimental redox potential and total energy interaction (calculated between internal tetrahedron (XO4n-), and rest of Kegging anion skeleton, (W12O36)) were designated. Taking into account the similarity of XW12O40n- and XMo12O40n- systems (in geometry and electronic structure), the estimated redox potential of molybdenum heteropolyanions (with X being p block elements) in different solvent were proposed.
ABSTRACT
The mesogenic species 4-(4-hexylcyclohexyl) isothiocyanatobenzene (6CHBT) was studied with density functional theory and molecular mechanics in order to investigate the molecular properties, interactions between dimers and to interpret the IR spectrum. Two types of calculations were performed for model systems containing single and double molecules of 6CHBT. Calculations (involving conformation analysis) for isolated species indicated that the trans isomer, in the equatorial-equatorial conformation, is the most energetically stable. The 6CHBT molecule is polar, with a rather high (4.43 D) dipole moment with negatively charged isothiocyanato (NCS) ligand. The dimer-dimer interaction energies show that the head-to-head configuration (where van der Waals attraction forces play the major role) is the most energetically stable. Vibrational analysis provided detailed assignment of the experimental infra-red (IR) spectrum.
