Deformation density in complex anions. IV

The deformation electron density in MgS2O3.6H2O has been determined at 120 K from a combination of X-ray and neutron diffraction data. Msub(r) = 244.56, Pnma, a = 9.324(2), b = 14.461(4), c = 6.862(1) A, V = 925.2(4) A3, Z = 4, Dsub(x) = 1.756 Mg m-3, F(000) = 512. Neutron diffraction: lambda = 0.8410 A, (sin theta/lambda)sub(max) = 1.02 A-1, μ = 0.158(1) mm-1, Rsub(w)(F) = 0.047 for 2771 independent reflections. X-ray diffraction: Nb-filtered Mo Kα, lambda = 0.71069 A (sin theta/lambda)sub(max) = 0.85 A-1, μ = 0.655 mm-1, Rsub(w)(F) = 0.026 for 2489 independent reflections. Peaks of about 0.25 eA-3 are observed at the midpoints of the S-O and S-S bonds. Extended lone-pair regions up to 0.03 eA-3 are found at the back of the sulfate O atoms. The lone-pair density at the terminal S atom is rather diffuse. All three independent water molecules show O-H bond peaks of 0.35-0.40 eA-3. Their O lone-pair peaks amount to 0.30-0.37 eA-3 and are considerably extended normal to the HOH plane. (Auth.)