A short dynamically symmetrical hydrogen bond in the structure of K[Mg(H0.5SO4)2(H2O)2

Abstract

The Mg atoms in the title compound, magnesium potassium hydrogendisulfate(3-) dihydrate, are found at the centres of symmetry at the unit cell corners and are octahedrally coordinated by two water molecules and the O atoms from four SO 4 tetrahedra to form infinite krohnkite-like Mg(H 0.5 SO 4 ) 2 (H 2 O) 2 chains running down the a axis. The sulfate and hydrogensulfate ions are coupled to form an (SO 4 HSO 4 ) 3- group with O...O 2.478 (3) A and with the H atom disordered around a symmetric double-minimum potential well. Crossed channels along the a and b axes are filled by tenfold-coordinated K atoms