TM4B18 0/- (TM = Hf, Ta, W, Re, Os): new structure construction with TM doped B wheel units.

Abstract

We report the global search for the lowest energy structures of the transition metal (TM) doped B clusters, TM4B180/− (TM = Hf, Ta, W, Re, Os) and their electronic properties. A combination of the comprehensive genetic algorithm (CGA) method with density functional theory (DFT) calculations shows that they are composed of four planar TM@B9 wheel units by sharing B atoms, except for Os4B180/−, which consists of two types of planar molecular wheels of Os@B7 and Os@B8. Among these nanoclusters, it is found that the Ta4B18 cluster has a closed-shell with a large HOMO–LUMO gap of 2.61 eV. Adaptive natural density partitioning analysis (AdNDP) reveals that the Ta4B18 cluster has σ antiaromaticity and π aromaticity, i.e., a conflicting aromaticity. The simulated photoelectron spectra (PES) of all anionic clusters are also provided for future experimental investigations.