Coordination Chemistry of Thorium Supported by a Single Polyoxoalkoxide Ligand

Abstract Actinide-polyoxometalate (An-POM) literature is dominated by the formation of 1:2 An(POM)2 sandwich-type complexes. Here, we report selective formation of a 1:1 An-POM complex using non-aqueous methods. Treatment of the lacunary POM precursor, (TBA)2[Mo5O13(OMe)4NO][Na(MeOH)], or the 1:2 Th-POM sandwich-type complex, (TBA)2[Th{Mo5O13(OMe)4NO}2], with ThCl4·2DME (DME = dimethoxyethane) in dimethylformamide leads to selective formation of the 1:1 Th-POM complex, (TBA)[ThCl2(DMF)2Mo5O13(OMe)4NO]. (TBA)[ThCl2(DMF)2Mo5O13(OMe)4NO] represents a rare example of an An-POM complex which possesses multiple labile ligands (DMF/Cl–) in its inner coordination sphere, providing an opportunity to study fundamental coordination chemistry processes. We report initial investigations probing neutral ligand exchange, halide abstraction, and salt metathesis at the thorium center supported by a POM, isolating a series of mixed-ligand species spanning a range of Th coordination geometries. This work establishes a versatile route to the controlled modification of actinide coordination environments in An-POM chemistry.