On evaporation of an aqueous mixture of M(II) sulfate (M(II) = Mn, Co, Ni, Cu, Zn or Cd) and benzylammonium sulfate in a molar ratio of 1:2 at room temperature in the presence of sulphuric
acid, double sulfates of only Mn, Cu and Cd were obtained. The stoichiometries of the compounds were determined by means of
elemental and TG analysis. It was concluded that these compounds have the same general formula: M(C6 H5 CH2 NH3 )2 (SO4 )2 4H2 O. These compounds have the same stoichiometry as that of the corresponding double sulfates with ethanolammonium cation,
but have different crystal structures.
The thermal decompositions of the investigated compounds in the temperature range from ambient temperature up to 1000C take
place in a similar way, in three well-differentiated stages, but with different pathways in the second and third stages. Metal
oxides were obtained as final products.