Study of the NpO

ArticleinRussian Journal of Coordination Chemistry 31(11):804-808 · January 2005with5 Reads
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    Abstract

    A new neptunium(VI) complex [(NpO2)(CrO4)(H2O)] ⋅ 4H2O (I) was synthesized, its crystal structure was determined, and the IR and near-IR absorption spectra were measured. The unit
    cell parameters are: a = 8.634(4) Å, b = 11.119(4) Å, c = 9.410(3) Å, β = 92.40(3)°, space group P21/c, Z = 4, V = 902.6(6) Å3, R = 0.048, wR(F
    2) = 0.054. The crystal structure of the compound is composed of the [(NpO2)(CrO4)(H2O)]
    n
    layers and the crystal water molecules located between the layers. The coordination polyhedron of neptunium is a pentagonal
    bipyramid whose equatorial plane is formed by the oxygen atoms of two bridging water molecules and three chromate ions. The
    Np(VI) complexation with the chromate ions in an aqueous solution at μ = 1 was studied by spectrophotometry. The stability
    constants for 1 : 1 and 1 : 2 complexes were calculated, logβ1 = 3.19(2), logβ2 = 3.93(2), respectively.