Crystal structure of the aquachloro complex of neptunium(V) with cesium CsNpO2Cl2(H2O)

The crystal structure of a new complex compound of neptunium(V) with the formula Cs[NpO2Cl2(H2O)] has been investigated by x-ray diffraction analysis and IR spectroscopy. The crystals are monoclinic, and the parameters of the crystal lattice are as follows: a = 1.171(2), b = 0.699(2), c = 0.876(2) nm, γ = 93.1(3)0, space group P21(P21/n), Z = 4, rho calc = 4.55 g/cm3. The structure was determined by the heavy-atom method with the use of photographic diffraction data and refined by the least-squares method in the block-diagonal isotropic-anisotropic approximation to R = 0.139. The structure is made up of infinite anion chains of [NpO2Cl2(H2O)]/sub n//sup n-/ and C5+ cations. The coordination polyhedron of neptunium is a slightly distorted [NpO2Cl4(H2O)]/sub n//sup n-/ pentagonal bipyramid. The Np-O distances in the NpO2+ oxo cations are equal to 0.180(3) and 0.181(3) nm, and the O-Np-O angle is equal to 176(2)0. The mean value of the Np-Cl distances is equal to 0.287 nm