Convenient Access To Thorium Chemistry

The burgeoning use of nonaqueous thorium chemistry in catalysis and materials science could benefit from a trio of anhydrous thorium complexes created by a team of Los Alamos National Laboratory chemists (Chem. Commun., DOI: 10.1039/b923558b). The complexes also could improve the prospects for developing thorium-based nuclear-power reactors (C&EN, Nov. 16, 2009, page 44). Anhydrous halide complexes are key starting points for synthesizing transition-metal, lanthanide, and actinide compounds. However, preparing thorium halides is hampered by tricky reactions that require harsh conditions and scarce thorium metal. Seeking a better approach, Thibault Cantat, Brian L. Scott, and Jaqueline L. Kiplinger refluxed commercially available thorium nitrate, Th(NO₃)₄(H₂O)₅, with 12 M 
HCl to produce ThCl₄(H₂O)₄ in quantitative yield under mild conditions. The team then used a novel combination of anhydrous HCl and (CH₃)₃SiCl to remove the coordinated water molecules and replace them with dimethoxyethane (DME), 1,4-dioxane, or tetrahydrofuran solvent molecules to make the three new reagents. Kiplinger and coworkers demonstrated the versatility of ThCl₄(DME)₂ by using it to prepare thorium alkoxide, amide, metallocene, and other compounds on multigram scales.