A quasi-plane IrB18- cluster with high stability.

The structural evolution of neutral and anionic iridium-doped boron (B) clusters, IrBn0/- with n = 10-20, has been studied by the Crystal structure AnaLYsis by Particle Swarm Optimization (CALYPSO) method and density functional theory (DFT) calculations. The IrB18- cluster with a quasi-plane structure and high stability is uncovered. Molecular orbital (MO) and adaptive natural density partitioning (AdNDP) analyses indicate that the high stability of the IrB18- cluster is attributed to the strong covalent interactions between the 5d orbitals of the Ir atom and the 2p orbitals of the surrounding B atoms. The present results offer new insights and considerably extend our understanding of the structural evolution and electronic properties of other metal-doped B clusters.

NbB12-: a new member of half-sandwich type doped boron clusters with high stability.

A theoretical study of geometrical structures and electronic properties of niobium-doped boron clusters is performed using the CALYPSO approach for the global minimum search followed by density functional theory calculations. It is found that the global minima obtained for the neutral clusters correspond to the half-sandwich structures at n = 10-17 and the tubular-type structures at n = 18-20. The geometrical patterns in the anion series are more complex. The geometries undergo a transformation from the wheel-like structure of NbB10- to the half-sandwich ones beginning at n = 11 and finally to the drum-shaped structures at n ≥ 18. A fascinating NbB12- cluster is uncovered by our structural search, which shows robust stability and can be considered as a new member of the half-sandwich transition metal doped boron clusters. The chemical bond analysis indicates that the high stability is due to the strong interactions between the Nb atom and the B12 host as well as to the strong B-B covalent bonds. Our study will enrich the database of geometrical structures of transition metal doped boron clusters and will stimulate future synthesis of boron-based nanomaterials.

Exhaustive exploration of MgBn (n = 10-20) clusters and their anions.

To understand the effect of magnesium atom doping on boron clusters, here we report the lowest-lying energy structures and electronic properties of neutral and monoanionic magnesium-boron clusters, in which boron atoms range in size from 10 to 20, in the framework of a CALYPSO structural search and DFT calculations. One of the most stable combinations is MgB18, which adopts an unexpected tubular drum-shaped geometry that is found for the first time in boron clusters doped with alkaline-earth metal atoms. The stability of the MgB18 cluster mainly stems from the intense electrostatic interaction between the B18 skeleton and the Mg atom.