A quantum topological study of the electron density in monomers and dimers of acyclic azathiens with aromatic substituents

A theoretical study of electron density, ρ(r), and the Laplacian (ab initio, DFT B3LYP/6-31G(d, p) basis set) has been carried out for nine molecules of azathiens with aryl substituents (Ar-N=S=N-Ar₁) and for sixteen dimers corresponding to typical arrangements of neighboring molecules in the crystal structures of Ar-N=S=N-Ar₁. A dependence was established of the values of the electron density at (3, ?1) critical points in the area of inter-stack and intra-stack atom-atom contacts on the internuclear distance.     

Why ionic liquids can possess extra solvent power

We use the Flory-Huggins theory to demonstrate conditions of extra solvent power of ionic liquids. The short-range interactions between anions, cations, and molecules of the solute are taken into account. We find that solvent power of the ionic liquids is enhanced if non-Coulomb interactions between the anions and cations are repulsive. The mechanism responsible for the extra solvent power is related to the "shielding" of the anion-cation interactions by the molecules of the solute.     

Atoms-in-molecules study of intra- and intermolecular bonding in the pentaerythritol tetranitrate crystal

Chemical bonding in the pentaerythritol tetranitrate crystal based on the experimental electron density obtained from X-ray diffraction data at 100 K and theoretical calculations at the experimental molecular geometry have been analyzed in terms of the Quantum Theory of Atoms in Molecules. Features of the intra- and intermolecular bond critical points and the oxygen atom lone-pair locations are discussed. Numerous intermolecular bonding interactions, including O...H and O...O, have been found and characterized. Atomic charges and atomic energies were integrated and compared with those for similar compounds. The N-O topological bond orders have been calculated for the first time, and the PETN atomic valences have been estimated.