Molecular cyclo-P(3) complexes of the rare-earth elements via a one-pot reaction and selective reduction

Synthesis of new organo-lanthanide polyphosphides with an aromatic cyclo-[P(4)](2−) moiety and a cyclo-[P(3)](3−) moiety is presented. For this purpose, the divalent Ln(II)-complexes [(NON)Ln(II)(thf)(2)] (Ln = Sm, Yb) ((NON)(2−) = 4,5-bis(2,6-diisopropylphenyl-amino)-2,7-di-tert-butyl-9,9-dimethylxanthene) and trivalent Ln(III)-complexes [(NON)Ln(III)BH(4)(thf)(2)] (Ln = Y, Sm, Dy) were used as precursors in the reduction process of white phosphorus. While using [(NON)Ln(II)(thf)(2)] as a one-electron reducing agent the formation of organo-lanthanide polyphosphides with a cyclo-[P(4)](2−) Zintl anion was observed. For comparison, we investigated a multi-electron reduction of P(4) by a one-pot reaction of [(NON)Ln(III)BH(4)(thf)(2)] with elemental potassium. As products molecular polyphosphides with a cyclo-[P(3)](3−) moiety were isolated. The same compound could also be obtained by reducing the cyclo-[P(4)](2−) Zintl anion within the coordination sphere of Sm(III) in [{(NON)Sm(III)(thf)(2)}(2)(μ-η(4):η(4)-P(4))]. Reduction of a polyphosphide within the coordination sphere of a lanthanide complex is unprecedented. Additionally, the magnetic properties of the dinuclear Dy(III)-compound bearing a bridging cyclo-[P(3)](3−) moiety were investigated.