Novel heptavalent actinide compounds: tetrasodium dihydroxidotetraoxidoneptunate(VII) hydroxide dihydrate and its plutonium analogue
摘要:
The title compounds, Na-4[NpO4(OH)(2)]OH center dot 2H(2)O and Na-4[PuO4(OH)(2)]OH center dot 2H(2)O, are isostructural and isomorphous, and contain complex [AnO(4)(OH)(2)](3-) anions (Ac is an actinide)in the form of distorted tetragonal bipyramids, Na+ cations, crystallization water molecules and outer-sphere OH groups. The complex [AnO(4)(OH)(2)](3-) anions occupy general positions and the coordinated OH groups deviate significantly from a centrosymmetric relative orientation. The [AnO(4)(OH)(2)](3-) anions exhibit anisotropic actinide contraction; the shortening of the An-O(hydroxide)bonds on going from Np to Pu is greater than that of the AnO(4) groups.