Chemical Physics and Properties of ThPt$_2$

ThPt$_2$ crystallizes with a unique type of structure (space group $I4/mmm$, $a = 4.1569(2)$\,\AA, $c = 14.3678(6)$\,\AA, which belongs to the group of the close-packed tetragonal structures (Pearson symbol $tI12$). An analysis of the chemical bonding by the electron density/electron localizability approach reveals formation of two-dimensional platinum anions separated by the Th cations. Measurements of magnetic susceptibility, electrical resistivity and specific heat show ThPt$_2$ to be diamagnetic with good metallic conductivity ($rho(300\,K) \approx 8.5 \mu\Omega$\,cm). The properties are in good agreement with the calculated electronic structure with a low DOS ($N(E_F) = 0.92$ states eV$^{-1}$ f.u$^{-1}$). The stability of the compound with respect to other possible structural modifications was studied theoretically.