Charge density distribution in thiosulfates: Na2S2O3 and MgS2O3.6H2O

Static deformation densities in both Na2S2O3 and MgS2O3.6H2O were derived by multipole refinement of X-ray diffraction data collected at 120 K. The deformation density is very similar in both thiosulfate groups. The lone-pair density at the hydrate O atoms is affected by cation and hydrogen-bond influences. Net atomic charges obtained by fuzzy-boundary integration are unrealistic for Na and Mg owing to the diffuse nature of the metal 3s shell. For H atoms contracted valence shells (ksub(H)=1.4) should be used. Dipole moments for the hydrate molecules range from 1.6 to 2.4 D (1D=3.3x10-30Cm) depending on the partitioning model employed. (orig.)