Valence‐Shell Electron‐Pair Repulsion Theory Revisited: An Explanation for Core Polarization

Abstract

Valence‐shell electron‐pair repulsion (VSEPR) theory constitutes one of the pillars of theoretical predictive chemistry. It was proposed even before the advent of the concept of “spin”, and it is still a very useful tool in chemistry. In this article we propose an extension of VSEPR theory to understand the core structure and predict core polarization in the main‐group elements. We show from first principles (Electron Localization Function analysis) how the inner‐ and outer‐core shells are organized. In particular, electrons in these regions are structured following the shape of the dual polyhedron of the valence shell (3rd period) or the equivalent polyhedron (4th and 5th periods). We interpret these results in terms of “hard” and “soft” core character. All the studied systems follow this trend, providing a framework for predicting electron distribution in the core. We also show that lone pairs behave as “standard ligands” in terms of core polarization. The predictive character of the model was tested by proposing the core polarization in different systems not included in the original set (such as XeF4 and [Fe(CN)6]3−) and checking the hypothesis by means of a posteriori calculations. From the experimental point of view, the extension of VSEPR to the core region has consequences for current crystallography research. In particular, it explains the core polarization revealed by high resolution X‐ray experiments.

Covalent and Non-covalent Noble Gas Bonding Interactions in XeFn Derivatives (n = 2–6): A Combined Theoretical and ICSD Analysis

“…A variety of Lewis bases and anions have been selected to analyze the influence of the basicity and neutral/anion nature of the donor on the interaction energies. We also represent the expected directionality assuming the stereo-active character of the lone pairs and their location is proposed based on the well-known valence-shell electron-pair repulsion (VSEPR) theory, that has been recently revisited (Munárriz et al, 2019).…”

Effects of lithium on the electronic properties of porous Ge as anode material for batteries

“…This indicates that there is a charge transfer between the Li and Ge where the Li donates its charge to the adjacent Ge where a lone pair is formed, according to the Valence‐Shell Electron‐Pair Repulsion (VESPR) theory. [ 66 ] This indicates that this bond has a more ionic nature, whereas the rest of the bonds can be identified as covalent. Worth noticing, is also a high degree of ionicity in the GeH bonds with more localization of electrons around the H atoms.…”

“…the Valence-Shell Electron-Pair Repulsion (VESPR) theory. [66] This indicates that this bond has a more ionic nature, whereas the rest of the bonds can be identified as covalent. Worth noticing, is also a high To complement the observations of the electron density difference and the ELF we developed a Hirshfeld population analysis of the structures shown in Figure 3 (supplementary material).…”

Energetics of Electron Pairs in Electrophilic Aromatic Substitutions

“…In a previous work [ 14 ] we have shown how the abovementioned coupling recovers and justifies the bond charge model (BCM) proposed by Parr and Borkman [ 15 , 16 ]. To do that we exploited the topology induced by the Electron Localization Function (ELF) proposed by Becke [ 17 ], given its ability to define electron pair regions in real space [ 18 ], and its good performance in the understanding of chemical properties and structure [ 19 , 20 ], as well as in reactivity [ 21 , 22 ]. We coupled the ELF with the interacting quantum atoms (IQA) approach [ 23 , 24 ], a powerful real-space quantum-chemical topology tool that allows partitioning the total energy of a system into chemically meaningful contributions, and has also been successfully applied in the analysis of a number of chemical phenomena from an intuitive chemical bond perspective [ 25 , 26 , 27 ].…”