Heterometallic Clusters with Thorium–Rhodium Bonds Supported by Double-Layer Nitrogen–Phosphorus Ligands

The investigation of metal–metal bonds involving f-block actinides has significantly lagged behind extensive research on d-block transition metal bonds. Species featuring thorium-transition metal bonds are exceptionally rare. In this study, we report the synthesis of the first species containing Th–Rh bonds. Using two nitrogen–phosphorus ligands, [CH3N(CH2CH2NHPiPr2)2] and {[CH2O(CH2)2NHPiPr2]2}, we synthesized the Th(IV) chloride precursors 1 and 5. Reactions of precursor 1 with [RhCl(COD)]2 or [IrCl(COD)]2 at room temperature produced heterometallic clusters 2 and 3, respectively. Similarly, precursor 5 reacted with [RhCl(COD)]2 or [IrCl(COD)]2 under the same conditions to yield analogues 6 and 7. Notably, heating complexes 1 or 5 with [RhCl(COD)]2 at 90 °C led to the formation of complexes 4 and 8, each featuring two Th–Rh bonding interactions. The Th–Rh bonding interaction in complex 8 is stronger than that in complex 7, as confirmed by both experimental observations and theoretical analysis.