Applicability of transferable multipole pseudo-atoms for restoring inner-crystal electronic force density fields. Chemical bonding and binding features in the crystal and dimer of 1,3-bis(2-hydroxyethyl)-6-methyluracil

Abstract

We considered it timely to test the applicability of transferable multipole pseudo-atoms for restoring inner-crystal electronic force density fields. The procedure was carried out on the crystal of 1,3-bis(2-hydroxyethyl)-6-methyluracil, and some derived properties of the scalar potential and vector force fields were compared with those obtained from the experimental multipole model and from the aspherical pseudo-atom model with parameters fitted to the calculated structure factors. The procedure was shown to accurately replicate the general vector-field behavior, the peculiarities of the quantum potentials and the characteristics of the force-field pseudoatoms, such as charge, shape and volume, as well as to reproduce the relative arrangement of atomic and pseudoatomic zero-flux surfaces along internuclear regions. It was found that, in addition to the quantum-topological atoms, the force-field pseudoatoms are spatially reproduced within a single structural fragment and similar environment. In addition, the classical and nonclassical hydrogen bonds in the uracil derivative crystal, as well as the H...O, N...O and N...C interactions in the free π-stacked dimer of the uracil derivative molecules, were studied using the potential and force fields within the concepts of interatomic charge transfer and electron lone pair donation–acceptance. Remarkably, the nitrogen atoms in the N...O and N...C interactions behave rather like a Lewis base and an electron contributor. At the same time, the hydrogen atom in the H...O interaction, being a Lewis acid, also participates in the interatomic electron transfer by acting as a contributor. Thus, it has been argued that, when describing polar interatomic interactions within orbital-free considerations, it makes more physical sense to identify electronegative (electron occupier) and electropositive (electron contributor) atoms or subatomic fragments rather than nucleophilic and electrophilic sites.

Carbon Dioxide Electroreduction and Formic Acid Oxidation by Formal Nickel(I) Complexes of Di‐isopropylphenyl Bis‐iminoacenaphthene

“…Thus, the coordination bonds Ni−N and Ni−C in [(dpp–bian)Ni(COD)] − are formed through the donor–acceptor mechanism. Notably, in our case, the direction of electron pair donation is opposite to the direction of charge transfer for all coordination bonds [51,52] …”

“…Notably, in our case, the direction of electron pair donation is opposite to the direction of charge transfer for all coordination bonds. [51,52]…”

Solubility- and melting-based approaches to evaluate the inner-crystal enantiophobia and enantiophilia undergoing a structural change within a homologous series, exemplified by chiral glycerol ethers

“…However, the usability of thermochemical parameters for melting to assess chiral discrimination is a priori doubtful, since the melt may preserve short-range order and can reproduce at least a part of the intermolecular interactions specific to a crystalline phase of a substance. 40,41,43,44 Furthermore, in the equilibrium melting process, the change in the free energy is zero, and melting usually occurs at a temperature well above than the standard conditions. Nevertheless, it is possible to use the difference between the free energies of a solid phase and its melt, corrected to the standard conditions (for example, 20 °C), as a numerical characteristic of melting.…”