Molecular cyclo-P3 complexes of the rare-earth elements via a one-pot reaction and selective reduction.

Synthesis of new organo-lanthanide polyphosphides with an aromatic cyclo-[P4]2- moiety and a cyclo-[P3]3- moiety is presented. For this purpose, the divalent LnII-complexes [(NON)LnII(thf)2] (Ln = Sm, Yb) ((NON)2- = 4,5-bis(2,6-diisopropylphenyl-amino)-2,7-di-tert-butyl-9,9-dimethylxanthene) and trivalent LnIII-complexes [(NON)LnIIIBH4(thf)2] (Ln = Y, Sm, Dy) were used as precursors in the reduction process of white phosphorus. While using [(NON)LnII(thf)2] as a one-electron reducing agent the formation of organo-lanthanide polyphosphides with a cyclo-[P4]2- Zintl anion was observed. For comparison, we investigated a multi-electron reduction of P4 by a one-pot reaction of [(NON)LnIIIBH4(thf)2] with elemental potassium. As products molecular polyphosphides with a cyclo-[P3]3- moiety were isolated. The same compound could also be obtained by reducing the cyclo-[P4]2- Zintl anion within the coordination sphere of SmIII in [{(NON)SmIII(thf)2}2(μ-η4:η4-P4)]. Reduction of a polyphosphide within the coordination sphere of a lanthanide complex is unprecedented. Additionally, the magnetic properties of the dinuclear DyIII-compound bearing a bridging cyclo-[P3]3- moiety were investigated.