The First Beryllium Periodate: Be(H₄IO₆)₂.4H₂O

The title compound, beryllium tetrahydrogenhexaoxoiodate(VII) tetrahydate, is built up from slightly deformed Be(OH₂)₄ tetrahedra (a,b) and IO₂(OH)₄ octahedra (A,B) with cis configuration of the oxo ligands. They are arranged along [001] forming layers with stacking aBAbABaBAbAB. The [H₄IO₆]⁻ and Be(OH₂)₄²⁺ ions are held together by a network of eight independent hydrogen bonds of different strength. Two of the H atoms of [H₄IO₆]⁻ are disordered over O—H↔H—O split positions.