Superatomic chemistry

Exploring the properties of new super-chalcogens based on multiple electron counting rules: a combined DFT and ab initio study on [M(B2C4X6)2]2- dianion clusters

The theoretical exploration of the super-chalcogen properties of multi-charged sandwich structures whose geometry simultaneously satisfyies the octet rule and Hückel's 4n+2 rule is reported here via a case study of dianion clusters [M(B2C4X6)2]2- (M = Be, Mg or Ca; X = H, F or Cl). The properties of these dianion clusters [M(B2C4X6)2]2- are close to or even superior to those of traditional clusters based on separate electron-counting rules, i.e., the octet rule and Hückel's 4n+2 rule. At the theoretical level of combined ab initio and DFT methods, these clusters, including halogen-substituents (F, Cl) are super-chalcogens due to their high first vertical electron detachment energy (FVDE), of which the largest value is 1.64 eV. This may be attributed to the strong ability of halogen-substituents (F, Cl) to attract an extra electron, according to an analysis of the distribution of the extra electron, and the spin density and the contribution of HOMO orbitals, leading to a larger spatial extent of the extra electron on both the ring skeleton and halogen ligands, which will lower the electronic kinetic energy according to fundamental quantum mechanics.

Theoretical Insights into the Geometrical Evolution, Photoelectron Spectra, and Vibrational Properties of YGe n - (n = 6-20) Anions: From Y-Linked to Y-Encapsulated Structures

The structural evolution behavior of germanium anionic clusters doped with the rare-earth metal yttrium, YGe n - (n = 6-20), has been investigated using a mPW2PLYP density functional scheme and an ABCluster structure searching technique. The results reveal that with increasing cluster size n, the structure evolution pattern is from the Y-linked framework (n = 10-14), where Y serves as a linker (the Y atom bridges two germanium subclusters), to the Y-encapsulated framework (n = 15-20), where the Y atom is located in the center of the Ge cage. The simulated PES spectra show satisfying agreement with the experimental PES spectra for n = 12-20, which reveals that the global minimum structures reported here are reliable. In particular, the anionic YGe16 - nanocluster is found to be the most stable structure in the size range of n = 6-20 through analyzes of the relative stability, highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gap, spherical jellium model, and isochemical shielding surface. Moreover, spectral properties such as infrared and Raman spectra were reported. In addition, the UV-vis spectra of the YGe16 - nanocluster are in good agreement with solar energy distribution, showing that such substances serve as multifunctional building blocks to be potentially used in optoelectronic devices or solar energy converters.