Structural and Electronic Properties of Medium-Sized Aluminum-Doped Boron Clusters AlB_n and Their Anions

Abstract

Binary boron-based compounds are expected to possess unique molecular architecture and chemical bonding. Here, we explore how incorporation of a valence isoelectronic Al atom into boron clusters containing from 10 to 20 atoms modifies the structures and properties of the initial clusters. The global minima structures of neutral and anionic Al-doped boron cluster in the size range from 10 to 20 have been identified using the Crystal structure AnaLYsis by Particle Swarm Optimization method. The states with the promising geometrical structures are reoptimized using density functional theory and tripleζ basis sets. It is found that the geometries of the ground states of the AlB n and AlB n − clusters possess planar, quasi-planar, and exohedral topologies. A nearly circular planar AlB 18 − cluster with C 2v symmetry and a large energy gap 2.98 eV has been discovered. The calculated photoelectron spectra of the anions are well in accord with the experimental spectra. The chemical-bonding analysis suggests that both large HLG and double π-aromaticity have much contribution to the electronic stability of AlB 18 − cluster. Our results elucidate the structural growth behavior of Al-doped boron clusters and enrich the growth pattern and chemical bonding nature of boron-based clusters.

Global optimization of chemical cluster structures: Methods, applications, and challenges

“…Using different variants of GA, (E = BH, C, Si, Ge) clusters were found to be star shaped [236–239] and aromatic. For some clusters like [240–242], both anionic and neutral forms were studied. The structures, which were obtained with CALYPSO, revealed that except for a few cases, anionic and neutral GMs have very similar geometries.…”

The binary aluminum scandium clusters AlxScy with x + y = 13: when is the icosahedron retained?

“…10 For the doped aluminum Al 12 X 2À , while the beryllium, X ¼ Be, sits at the center of an aluminum icosahedral cage due to its small atomic radius, the remaining dopants with X being an alkaline earth metal having larger atomic radius, favor its attachment outside at the surface. [11][12][13] Although the aluminum doped boron clusters B 12 Al favor a quasi-planar shape, 14 it was also found that other dopants which belong to the same group IIIA as aluminum including B and Ga, can substitute the Al atom(s) at the center of icosahedral cage Al 13 . 15,16 An investigation of the cationic clusters Al 12 X + , with X being a tetravalent atom including C, Si, Ge, Sn, and Pb, showed that except for the low symmetry structure of Al 12 C + , the remaining structures of Al 12 X + prefer an icosahedral shape.…”

Structural transformations in boron clusters induced by metal doping

“…106 B 10 Al is also an umbrella-like structure. 139 Furthermore, photoelectron spectra along with computations revealed B 10 Al − is not structurally modified, but rather the Al coordinates with three B atoms at the edge. 135 A Sc atom, as shown, does not modify the original B geometry, so, B 10 Sc is a 10-5 structure, 65,90 similar to other B 10 TM (TM = Ni, Nb, Zr, Na, Mo, and Mo − ) clusters.…”