Why Does a B12H12 Icosahedron Need Two Electrons to be Stable: A First-Principles Electron-Correlated Investigation of B12Hn (n=6, 12) Clusters

In this work, we present large-scale electron-correlated computations on various conformers of B12H12 and B12H6 clusters to understand the reasons behind the high stability of dianion icosahedron (I-h) and cage-like B12H6 geometries. Although the B-12 icosahedron is the basic building block in some structures of bulk boron, it is unstable in its free form. Furthermore, its H-passivated entity, i.e., a B12H12 icosahedron, is also unstable in the free form. However, dianion B12H12 has been predicted to be stable as a perfect icosahedron in the free-standing form. To capture the correct picture for the stability of B12H122- and B12H6 clusters, we optimized these structures by employing the coupled-cluster singles and doubles (CCSD) approach and the cc-pVDZ basis set. We also performed the vibrational frequency analysis of the isomers of these clusters using the same level of theory to ensure the stability of the structures. For all of the stable geometries obtained from the vibrational frequency analysis, we additionally computed their optical absorption spectra using the time-dependent density functional theory (TDDFT) approach at the B3LYP/6-31G* level of theory. Our calculated absorption spectra could be probed in future experiments on these clusters.

Automated summary

In this work, large-scale electron-correlated computations were performed on B12H12 and B12H6 clusters to understand the high stability of dianion icosahedron and specific geometries. This research found that dianion B12H12 and certain geometric structures exhibit high stability.