Ln 2 (ClO 4 ) 2 (H 2 I 2 O 10 ) · 8H 2 O (Ln = Sm, Gd), a Lanthanide Perchlorate Mesodiperiodate forming a Novel Layer Structure

By slow evaporation of solutions containing Ln(ClO 4 ) 3 (Ln = Sm, Gd), H 5 IO 6 and an excess of HClO 4 , crystals of the title compounds could be obtained. Their structures were determined by single‐crystal X‐ray diffraction. The compounds crystallize in the monoclinic crystal system, space group P 2 1 / c . They contain Ln 3+ ions, which are coordinated by [H 2 I 2 O 10 ] 4— anions forming two‐dimensional, cationic networks. These are separated by perchlorate ions, forming a layered structure.