On Close Parallels between the Zintl-Based Superatom Ge₉Be and Chalcogen Elements

Abstract

Ever since the concept of superatoms was brought forward in the 1990s, various specific types of clusters have been proposed to mimic atomic properties and enrich the "threedimensional periodic table". In this work, a Zintl cluster, namely, Ge 9 Be, has been certified eligible to join the superatom family, owing to its surprising similarity to chalcogen elements. Having 38 valence electrons, Ge 9 Be has an intrinsic desire to gain two additional electrons to achieve electronic shell closure, in which its quasi-chalcogen identity roots. Like oxygen-group elements, Ge 9 Be has the potential to form stable ionic compounds with lithium, beryllium, calcium, and superalkaline-earth atom FLi 3 . On the other hand, the combination of Ge 9 Be and the multiple valence superatom Al 7 − results in covalent compounds resembling carbon oxides. Close parallels have also been found between (Ge 9 Be) 2 -based compounds and common peroxides, further evidencing the superatom characteristics of Ge 9 Be. This finding puts forward an almost perfect superatom counterpart of group VIA elements and opens the door to characteristics-oriented design and synthesis of stable superatom motifs by utilizing solid Zintl clusters.

Role of Size and Composition on the Design of Superalkalis

“…Recently, it has been shown that Be@Ge 9 can be termed as a superatom as it mimics the chemistry of a chalcogen. 28 As discussed before, Be@Ge 9 requires two extra electrons for electronic shell closure, just as chalcogens do. However, unlike the boranes B n H n , the second electron in Be@Ge 9 is not bound as the second electron affinity of Be@Ge 9 2− is −2.05 eV.…”

“…15 Recently, it has been demonstrated that Be atom embedded inside Ge 9 mimics the properties of chalcogens. 28 Adding two Li atoms to the Be@ Ge 9 cluster can thus stabilize the Li 2 BeGe 9 cluster. Hence, we hypothesized that Li 3 BeGe 9 could also be considered as a superalkali.…”

On reactivity of superatom Be8C with nucleophiles to produce hydrogen

“…Quasi‐phosphorus character of the As 7 , As 11 , and Al 12 Cu clusters have been revealed by both theoretical and experimental works [14–18]. The Al 12 Be and Ge 9 Be clusters have been found to have chemical behavior reminiscent of chalcogens and can be viewed as their superatom mimics [19, 20].…”

“…Our previous study has reported a magic cluster, namely Be 8 C, which stands out among the Be n C series [30] with unique relative stability [20] and hence, may serve as a "superatomic" building block for nanoscale assemblies or materials. According to valence molecular orbital (MO) analysis, we notice that Be 8 C possesses a closed-shell electron configuration of 1S 2 1P 6 1D 4 2S 2 1D 6 , which is similar to that of 3s 2 3p 6 3d 10 4s 2 for Zn atom except that the 1D level of Be 8 C splits due to its non-spherical geometry (see Figure S1).…”

“…by both theoretical and experimental works [14][15][16][17][18]. The Al 12 Be and Ge 9 Be clusters have been found to have chemical behavior reminiscent of chalcogens and can be viewed as their superatom mimics [19,20].…”