The crystal structure of the anhydrous cadmium and mercuric sulfates

Abstract
The crystal structure of CdSO 4 and HgSO 4 has been determined with x-ray single-crystal data. The unit cell is orthorhombic with a = 4.704, b = 4.722, c = 6.565 Å for CdSO 4 and a = 4.785, b = 4.821, c = 6.581 Å for HgSO 4 . Z = 2, space group Pn 2 1 m . The SO 4 tetrahedron in both isotypic substances is distorted. The Cd and Hg atoms are surrounded by four O atoms in the form of a very distorted tetrahedron. The SO 4 tetrahedra share a corner with the MO 4 tetrahedra and form a three-dimensional network.