Tetrametallic Thorium Compounds with Th₄E₄ (E = S, Se) Cubane Cores

Area of Science:

• Organometallic chemistry
• Thorium chemistry
• Coordination chemistry

Background:

• Thorium chalcogenolates are precursors to tetrametallic thorium clusters.
• Ligand-based reductions offer a pathway to novel metal-chalcogen structures.

Purpose of the Study:

• To synthesize and characterize novel tetrametallic thorium compounds with a Th4E4 core.
• To investigate the influence of fluorinated ligands on the structure and properties of these compounds.

Main Methods:

• Synthesis via ligand-based reduction of elemental sulfur (S) or selenium (Se) with thorium chalcogenolates.
• Characterization using Nuclear Magnetic Resonance (NMR) spectroscopy and X-ray diffraction.
• Preparation involved in situ oxidation of Thorium (Th) metal with specific phenyl and pentafluorophenyl chalcogenide mixtures.

Main Results:

• Four tetrametallic thorium compounds with a distorted cubane Th4E4 core were successfully synthesized and characterized.
• The compounds exhibited distinct ligand coordination, with less nucleophilic pentafluorophenyl (C6F5) ligands at terminal sites and phenyl (Ph) ligands bridging metal centers.
• X-ray diffraction revealed a consistent crystal packing motif and crystallization in a body-centered tetragonal unit cell.
• Solution-state 77Se NMR spectroscopy confirmed the stability of the solid-state structures in pyridine.

Conclusions:

• Tetrametallic thorium clusters with Th4E4 cores can be effectively synthesized through ligand-based reductions.
• Ring fluorination significantly influences ligand binding preferences in these thorium clusters.
• The observed solid-state structures are retained in solution, indicating structural robustness.