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.

针对包含f区锕系元素（f-block actinides）的金属-金属键的研究，其研究进展显著滞后于针对d区过渡金属（d-block transition metal）键的广泛研究。含钍-过渡金属键的物种极为罕见。本研究首次报道了含Th–Rh键的化合物的合成。我们采用两种氮-磷配体（nitrogen–phosphorus ligands）[CH3N(CH2CH2NHPiPr2)2]与{[CH2O(CH2)2NHPiPr2]2}，成功合成了Th(IV)氯化物前驱体1与5。前驱体1在室温下分别与[RhCl(COD)]₂或[IrCl(COD)]₂反应，得到异金属团簇（heterometallic clusters）2与3。同理，前驱体5在相同条件下与[RhCl(COD)]₂或[IrCl(COD)]₂反应，得到其对应类似物6与7。值得注意的是，将配合物1或5与[RhCl(COD)]₂在90℃下加热，可得到各自具有两处Th–Rh成键作用的配合物4与8。经实验观测与理论分析证实，配合物8中的Th–Rh成键作用强于配合物7。