The stereochemistry of Tutton's salts X2[M(H2O)6](YO4)2

Neutron structure determinations have been made of Tutton's salts, X₂[M(H₂O)₆] (YO₄)₂, where Y = Se, X = K⁺, M = Cu²⁺; Y = S, X = K⁺, M = Ni²⁺, Cu²⁺, Zn²⁺; X = Rb⁺, Cs⁺, M = Cu²⁺. This work has shown that there are extensive hydrogen networks with almost linear hydrogen bonds from [M(H₂O)₆]²⁺ to (YO₄)^2?. The (H … O) distance increases in the Cu²⁺ 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(H₂O)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 XO₈⁺ dodecahedron increases with increased cation size, implying that the X⁺ polyhedron is maintaining its shape.