Supertetrahedrane and its boron analogs

Novel stable structures, viz., supertetrahedrane (C₁₀₄H₃₂), supertetraborane (B₁₀₄H₃₂), and mixed supertetracarboranes (B₆₄C₄₀H₃₂ and B₄₀C₆₄H₃₂), derived by substituting for carbon atoms in the diamond lattice by tetrahedra C₄ and B₄, respectively, and being supermolecular models of the corresponding carbon and boron crystalline structures were studied by the DFT B3LYP/6-311+G** method. The low difference in energies of the frontier orbitals indicate semiconduction properties of these compounds. The carbon-carbon, boron-boron, and carbon-boron bonds in the studied compounds are shorter than in diamond and in the borane or carboranes systems, respectively. Along with the calculated vibrational spectra, this indicates that their mechanical properties are similar to those of diamond. However, a considerably low density of these compounds shows their high potential possibility of applying them in aerospace technology.