Abstract
AsF3E as a representative of a molecular crystal has been chosen to find the precise localization of the lone pair (LP) E centroid 4s2 of As3+ and to enlighten the behavior of lone pair triplets of fluorine atoms. Starting from stereochemistry rationale, Density Functional (DFT) electronic structure calculations yielding the electron localization (ELF) mapping led to precise large crystal structure evolutions from basic X-rays data (V = 267.2Å3 at 193K), to (V = 230.5Å3) and under Van der Waals forces (DEW) V = 206.4Å3, and then under pressure P, all illustrated with ELF maps and band structures. Calibrated pressures up to 100 GPa exhibit the remarkable shrinking of all inter-atomic distances including As-E from 0.94Å down to 0.46Å, while the major three bonds As-F1, As-F2 and As-F3 are continuously expanding. The resulting picture of the application of pressure on AsF3 molecular structure leads to the progressive immersion of the 4s2 doublet within the electronic cloud with an original new status of As with its 4s2 E expressed as [AsE]3+. The expanded size becomes close to big LP-free K+, Ba2+ cations or LP characterized bismuth cation: [BiE]3+, which appear inserted in cubes or square anti-prisms with coordination number 8 (CN8) or in tricapped trigonal prisms with CN9.
Highlights
We focused on AsF3 E, where E designates AsIII 4s2 lone pair, to precisely address the features pertaining firstly to the stereoactivity of AsIII lone pair E on one hand, and on the other hand to focus on the significant role of the LPs brought by the fluorine atoms of the three pending As-F bonds
The As-F bonds are almost identical for the three kinds of As-Fi (i = 1,2,3) interactions, but large changes occur in the lower panel upon accounting for van der Waals forces (vdW) effects where As-F1 integrated COOP (iCOOP) intensity prevails versus As-F2 and As-F3 within the broader p-like VB, in perfect agreement with
In this work a thorough analysis highlighting the major changes brought into the molecular structure of arsenic trifluoride AsF3 E submitted via Density Functional (DFT)-electron localization function (ELF) to van der Waals corrections and high pressure treatments was performed
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Following our earlier research works on electron lone pair (LP) ns elements [1,2], some particular features on fluoride compounds of group VA trivalent elements prompted us to carefully settle their stereochemistry and to include the fluoride anions LP triplets For this purpose, we focused on AsF3 E, where E designates AsIII 4s2 lone pair, to precisely address the features pertaining firstly to the stereoactivity of AsIII lone pair E on one hand, and on the other hand to focus on the significant role of the LPs brought by the fluorine atoms of the three pending As-F bonds. Matter 2021, 6, 31 quantitative LP metrics, and on the other hand to follow AsF3 evolution at the atomic scale by accounting for van der Waals effects and under pressure (GPa) influence [4].
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