ESI-MS speciation analysis of neodymium and thorium complexed with nitrilotriacetic and picolinic acids

Exploring the Coordination of Plutonium and Mixed Plutonyl-Uranyl Complexes of Imidodiphosphinates

The coordination chemistry of plutonium(IV) and plutonium(VI) with the complexing agents tetraphenyl and tetra-isopropyl imidodiphosphinate (TPIP^- and TIPIP^-) is reported. Treatment of sodium tetraphenylimidodiphosphinate (NaTPIP) and its related counterpart with peripheral isopropyl groups (NaTIPIP) with [NBu₄]₂[Pu^IV(NO₃)₆] yields the respective Pu^IV complexes [Pu(TPIP)₃(NO₃)] and [Pu(TIPIP)₂(NO₃)₂] + [Pu^IV(TIPIP)₃(NO₃)]. Similarly, the reactions of NaTPIP and NaTIPIP with a Pu(VI) nitrate solution lead to the formation of [PuO₂(HTIPIP)₂(H₂O)][NO₃]₂, which incorporates a protonated bidentate TIPIP^- ligand, and [PuO₂(TPIP)(HTPIP)(NO₃)], where the protonated HTPIP ligand is bound in a monodentate fashion. Finally, a mixed U(VI)/Pu(VI) compound, [(UO₂/PuO₂)(TPIP)(HTPIP)(NO₃)], is reported. All these actinyl complexes remain in the +VI oxidation state in solution over several weeks. The resultant complexes have been characterized using a combination of X-ray structural studies, NMR, optical, vibrational spectroscopies, and electrospray ionization mass spectrometry. The influence of the R-group (R = phenyl or ⁱPr) on the nature of the complex is discussed with the help of DFT studies.