A Zn₂-supported B₇ wheel structure for the global minimum of the B₇Zn₂ cluster

In this work, we employ density functional theory (DFT) to explore the structure of boron clusters doped with two zinc atoms (B₇Zn₂ or Zn₂B₇). The results show that the most stable structure is a Zn₂ motif standing over a B₇ wheel, which is 0.89 eV lower in energy compared to the classical inverse-sandwich structure for B₇TM₂ (TM = transition metal) clusters. The characteristics of these systems are evaluated by the IR spectra to guide plausible experimental realization. In addition, density of states, and bonding characteristics were evaluated. Our results denote the formation of an intermediate Zn-Zn bond order given by the key electron-acceptor nature of the B₇ motif, leading to a depopulation of antibonding Zn-Zn orbitals and population of the respective bonding orbitals. Thus, the evaluation and use of more electron-deficient supporting ligands may trigger a quest for the design of plausible structures featuring larger Zn-Zn elusive bond orders in stable species.