Structural similarity between boron oxide Bn(BO)n 2- and boron hydride BnHn 2- dianions (n = 4-12)

The boron oxide dianions Bn(BO)n 2– (n = 4–12) are studied using DFT (B3LYP) method. Geometries of the global minima of Bn(BO)n 2– with n = 4–12 are found to be analogous to those of boron hydrides. All boron oxides considered exhibit large HOMO-LUMO gaps and high vertical detachment energies. Similar to BnHn 2– , the enhanced thermodynamic stabilities are established for Bn(BO)n 2– at n = 6, 10 and 12. Due to the strength of BO bonds, oxidation of boron clusters thus consistently leads to formation of exohedral boronyls that in turns behave as substituents replacing the hydrogen atoms. This structural similarity allows the shape of boron oxides to be predicted from boron hydrides. Nevertheless, the BO bonds are expected to be the preferred reaction sites of boron oxides.