Crystallographic observation of the transition from inner to outer complexes of the trivalent lanthanide series with diphenyldithiophosphinate

Sulfur-donor dithiophosphinic acids have demonstrated varying extractability among different Ln3+ ions. We herein present a comprehensive perspective on the interaction of diphenyldithiophosphinate (S2PPh2−) with the trivalent lanthanide series under hydrous conditions, characterized by single-crystal X-ray diffraction. For the first time, we systematically report single crystals demonstrating three distinct coordination modes throughout the lanthanide series, including inner-sphere complexes [NEt4][Ln(S2PPh2)4] (La ∼ Dy), outer-sphere complexes [NEt4][Ln(H2O)9][S2PPh2]4 (Eu ∼ Lu), and inner-outer hybrid complexes [Ln(S2PPh2)3(H2O)2] (Nd ∼ Tb).