Bonding features in Appel's salt from the orbital-free quantum crystallographic perspective

Abstract

Bonding properties in the crystal of 4,5-dichloro-l,2,3-dithiazolium chloride (Appel's salt) were studied using a combination of single-crystal high-resolution X-ray diffraction data and the orbital-free quantum crystallography approach. A QTAIM-based topological model shows the proximity of S—C and S—N bonds to the sesquialteral type and establishes the low S—S bond order in the l,2,3-dithiazolium heterocycle. It is found that the electrostatic potential carries the traces of a common positive area on the junction of interatomic zero-flux surfaces of S1 and S2 atomic basins; meanwhile the exchange energy density per particle shows perfectly here two separate minima through which the two bond paths run. Thus, the pair intermolecular interactions Cl−...S1 and Cl−...S2 formed by the common chloride anion placed near the center of the S—S bond are categorized as chalcogen bonds.

WinXPRO, 3DPlot and TrajPlot computer software: new options for orbital-free quantum crystallography studies

“…reaching a minimal value in the charge-shift S-S bond. This conclusion, in general, agrees with bond-order indices estimated from theoretical electron density: they decrease in a similar way (Bartashevich et al, 2021). The smaller the electronic potential energy at the b.c.p.s, the weaker the covalent bond strength.…”

“…Many other examples may be additionally found in very recent work by Tsirelson & Stash (2020, Bartashevich et al (2021) and Shteingolts et al (2021).…”

“…This approach arose recently from studies of electron density in crystals (Tsirelson & Ozerov, 1996;Gatti & Macchi, 2012;Stalke, 2012) within the framework of the orbital-free density functional theory (Wesolowski & Wang, 2013), information theory (Nalewajski, 2006), and an extension of Bader's quantum theory (Bader, 1990) of atoms in molecules and crystals Tsirelson, 2007). Early work has demonstrated the effectiveness of this approach (Shteingolts et al, 2021;Stash et al, 2021;Bartashevich et al, 2021). We report here the release of a software package consisting of the WinXPRO (version 3.4.51), 3DPlot (version 2.5.26) and TrajPlot (version 1.4.0.2) programs.…”

Real-Space Interpretation of Interatomic Charge Transfer and Electron Exchange Effects by Combining Static and Kinetic Potentials and Associated Vector Fields

“…The topology of 𝜑 𝑒𝑠 (𝒓) 54,57,58 in combination with 𝜌-basins is widely employed for describing electrostatic contribution for various interactions in associates and crystals. 14,15,66,17,[59][60][61][62][63][64][65] Further, the gap between 𝜑 𝑒𝑠 -and 𝜌-basins is attributed to phenomena of interatomic charge (electron) transfer and can be used to estimate it. 15 However, although 𝜑 𝑘 -basins (pseudoatoms) and corresponding kinetic force field have a robust physical definition, it is not clear for now how it can be exploited to retrieve chemical information.…”

“…15 The examination of electronic potentials can serve to enhance or even substitute the use of existing chemical descriptors: for example, the analysis of 𝜑 𝑒𝑚 (𝒓) can be considered as a viable or even preferable alternative to 𝜑 𝑒𝑠 (𝒓). 15,66 Nevertheless, it is worth noting the widespread use of 𝜑 𝑒𝑠 (𝒓) for the explanation and prediction of chemical behavior. [68][69][70][71][72][73][74][75][76] The Pauli potential 𝜑 𝑃 (𝒓)…”