Atomic Charges and Chemical Bonding in Y-Ga Compounds

Abstract

A negative deviation from Vegard rule for the average atomic volume versus yttrium content was found from experimental crystallographic information about the binary compounds of yttrium with gallium. Analysis of the electron density (DFT calculations) employing the quantum theory of atoms in molecules revealed an increase in the atomic volumes of both Y and Ga with the increase in yttrium content. The non-linear increase is caused by the strengthening of covalent Y-Ga interactions with stronger participation of genuine penultimate shell electrons (4d electrons of yttrium) in the valence region. Summing the calculated individual atomic volumes for a unit cell allows understanding of the experimental trend. With increasing yttrium content, the polarity of the Y-Ga bonding and, thus its ionicity, rises. The covalency of the atomic interactions in Y-Ga compounds is consistent with their delocalization from two-center to multi-center ones.

High-Pressure Synthesis and Chemical Bonding of Barium Trisilicide BaSi3

“…The ELI-D distribution in the penultimate shell of the barium atoms shows significant deviations from spherical symmetry (structuring [38], Figure 6, left pannel). Quantitative characterization of this trend and comparison to the recent results for YGa 6 , YGa and t -Y 5 Ga 3 [55] reveals fingerprints for the participation of the penultimate shell in the bonding interactions [38,56]. In the valence region of silicon, five different ELI-D maxima are observed.…”

Revealing Electronic Influences in the Semihydrogenation of Acetylene

“…For the series Ga 1– x Sn x Pd 2 , a linear dependence of the unit cell volume on the Sn content is observed as expected for a substitutional solid solution , (Figure S3), thus corroborating the smallest possible extent of structural changes. Following Vegard’s rule also indicates that the chemical bonding does not change markedly with increasing tin content . The additional electron causes the observed increase in ductility and segregation with increasing tin content.…”

“…Following Vegard's rule also indicates that the chemical bonding does not change markedly with increasing tin content. 40 The additional electron causes the observed increase in ductility and segregation with increasing tin content. Upon substitution, the coordination number of the Pd atoms does not change and the (Ga/Sn)−Pd (2.544−2.646 Å) as well as the Pd−Pd distances (2.809−2.889 Å) show the expected small variations.…”

La2Pd3Ge5 and Nd2Pd3Ge5 Compounds: Chemical Bonding and Physical Properties

“…Additional information can be extracted from the shape of QTAIM atoms. In fact, La is rather spherical, which is typical for cations in similar compounds, ,− and both Ge and Pd basins possess a polyhedral shape. What is more, not only the shared faces between Ge2 and Ge3 are flat, which is characteristic for homopolar bonds, but also those between Ge and Pd.…”