Using quantum chemistry methods B3LYP/6-31＋＋G（d,p） to optimize endohedral complexes X@（HBNH）12 （X=Li^0/＋, Na^0/＋, K^0/＋, Be^0/2＋, Mg^0/2＋, Ca^0/2＋, H and He）, the geometries with the lowest energy were achieved. Inclusion energy, standard equilibrium constant, natural charge, spin density, ionization potentials, and HOMO-LUMO energy gap were also discussed. The calculation predicted that X=Na^0/＋, K^0/＋, Mg^0/2＋, Ca^0/2＋, H and He are nearly located at the center of （HBNH）12 cluster. Li^＋ lies in less than 0.021 nm departure from the center. Li and Be^0/2＋ dramatically deviate from the center. （HBNH）12 prefers to enclose Li^＋, Be^2＋, Mg^2＋, and Ca^2＋ in it than others. Moreover, M@（HBNH）12 （M=Li, Na, K） species are ＂superalkalis＂ in that they possess lower first ionization potentials than the Cs atom （3.9 eV）.
Structures and thermodynamic properties of the imidoboranes （HBNH）n （n=1-16） have been investigated theoretically at the B3LYP/6-31G^＊ level of theory. Needle-shaped oligomers that violate the isolated square rule were found to be more stable than cage isomers. The needle-shaped oligomer with n=16 was predicted to be exceptionally stable at low temperature, hexamer and octamer clusters dominated the gas phase at higher temperature. The highest oligomerization degree of the spontaneous cluster fomation has been estimated. It was concluded that generation of the gas phase （HBNH）n clusters with oligomerization degree n ≥24 was viable, making these species possible intermediates involved in the gas phase generation of BN nanoparticles.
The structures, energies and aromaticity （the nuclear-independent chemical shifts,NICS） of AlCO-substituted semibullvalenes were investigated at the B3LYP/6-311＋G＊＊ level.Similar to BCO-substituted analogues, [2,6]-AlCO-semibullvalene is neutral bishomoaromatic.The NICS values reveal that the aromaticity of AlCO-substituted structures is smaller than that of BCO analogues.
Considering the isolobal analogy between two fragments CH and BCO, the calculations on the reactants, products, and transition states for the Claisen rearrangement of （BCO）n-substituted phenyl allyl ethers at the B3P86/ 6-311 ＋ G^＊＊ level was performed in this study. The transition states of （BCO）n-substituted systems have looser and more structures with dipole nature. The substitutions of CH by BCO do favor the reduction of the free energies of activation and the enhancement of stabilization of both reactants and products. A Marcus theory and frontier molecular orbitals were used to separate the thermodynamic and intrinsic contributions to the activation energies.
