Thorium and its compounds have been widely investigated as important nuclear materials. Previous research focused on the potential use of thorium hydrides, such as ThH2 , ThH4 , and Th4 H15 , as nuclear fuels. Here, we report studies of the anion, ThH5- , by anion photoelectron spectroscopy and computations. The resulting experimental and theoretical vertical detachment energies (VDE) for ThH5- are 4.09 eV and 4.11 eV, respectively. These values and the agreement between theory and experiment facilitated the characterization of the structure of the ThH5- anion and showed its neutral counterpart, ThH5 to be a superhalogen. ThH5- , which exhibits a C4v structure with five Th-H single bonds, possesses the largest known H/M ratio among the actinide elements, M. The adaptive natural density partitioning (AdNDP) method was used to further analyze the chemical bonding of ThH5- and to confirm the existence of five Th-H single bonds in the ThH5- molecular anion.
Keywords: actinides; anion photoelectron spectroscopy; hydrides; superhalogen; thorium.
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