Volatile β-diketonates of neptunium(IV) and (VI)

Abstract A series of new volatile β-diketonates of Np(IV) (in the unsolvated form and as adducts) and Np(VI) (as adducts) have been synthesized. The compounds isolated were identified by IR and NMR spectroscopy and chemical analysis. The sublimation capability of the substances was studied. Some Np(VI) complexes are shown to suffer partial or complete decomposition (depending mainly on the Np—neutral ligand bond strength) with partial formation of Np(IV) chelates during sublimation. The structure of the complexes (including geometrical isomerism) and stoichiometry of adduct formation were studied by NMR spectroscopy. From mass spectrometry, the composition of the complexes in the gas phase as well as their fragmentation schemes have been established. The temperature dependence of the saturated vapour pressure of a series of chelates was determined.