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

Abstract

Tetrametallic thorium compounds with a ThE core (E = S, Se) having a distorted cubane structure can be prepared by ligand-based reductions of elemental E with thorium chalcogenolates, prepared by in situ oxidation of Th metal with a 3:1 mixture of PhEEPh and FCEECF. Four compounds, (py)ThS(μ-SPh)(SCF), (py)ThS(μ-SPh)(SeCF), (py)ThSe(μ-SePh)(SeCF), and (py)ThSe(μ-SePh)(SCF), were isolated and characterized by NMR spectroscopy and X-ray diffraction. These compounds clearly demonstrate the chemical impact of ring fluorination, with the less-nucleophilic ECF ligands occupying the terminal binding sites and the EPh ligands bridging two metal centers. For this series of compounds, crystal packing and intermolecular π···π and H-bonding interactions result in a consistent motif and crystallization in a body-centered tetragonal unit cell. Solution-state Se NMR spectroscopy reveals that the solid-state structures are maintained in pyridine.

Heteroleptic Samarium(III) Chalcogenide Complexes: Opportunities for Giant Exchange Coupling in Bridging σ- and π-Radical Lanthanide Dichalcogenides

“…This effect also manifests in the Mulliken spin population analysis leading to more than five unpaired spins at the Sm ion, which increases with increasing size of the chalcogen (Figure S73). This is brought about by a poorer energy match of the 4f-manifold with the n p orbitals of the chalcogen such that Se 4p and Te 5p orbitals are energetically closer to the Sm 5d orbitals. ,, …”