Redetermination of the crystal structure of dipotassium imidobis(trioxosulphate) by neutron diffraction

Abstract

The crystal structure of the title compound has been redetermined from three-dimensional neutron diffraction data with 511 reflections. Z= 4 in the monoclinic space group C2/c, with cell dimensions a= 1 248.3(6), b= 749.9(4), c= 720.8(3) pm, β= 91.21(2)°. The structure was refined by full-matrix least-squares in the centric space group C2/c to R 0.056. The nitrogen in the anion was found to be on a two-fold axis and surrounded tetrahedrally by two groups and two half hydrogen atoms. Refinement in the non-centric space C_c gave R 0.058, with the nitrogen trigonally surrounded by the trioxosulphates and one hydrogen atom. This model was rejected on the basis of Hamilton's significance test.