The stereochemistry of Tutton's salts X2[ M(H 2O) 6]( YO 4) 2

Neutron structure determinations have been made of Tutton's salts, X₂[ M(H ₂O) ₆] ( YO ₄) ₂, where Y = Se, X = K ⁺, M = Cu ²⁺; Y = S, X = K ⁺, M = Ni ²⁺, Cu ²⁺, Zn ²⁺; X = Rb ⁺, Cs ⁺, M = Cu ²⁺. This work has shown that there are extensive hydrogen networks with almost linear hydrogen bonds from [ M(H ₂O) ₆] ²⁺ to ( YO ₄) ^2-. The (H … O) distance increases in the Cu ²⁺ series for X = K ⁺ to Cs ⁺ but there is no difference for the potassium copper salts when Y = Se or S. Three different distorted [ M(H ₂O) ₆] ²⁺ octahedra were found in the series (orthorhombic, tetragonal with two long and four short, or four long and two short bonds). The interatomic distances from X⁺ to the neighboring O in a distorted XO ₈⁺ dodecahedron increases with increased cation size, implying that the X⁺ polyhedron is maintaining its shape.