Synthesis and crystal structure of Fe6Ca2(SeO3)9Cl4 – a porous oxohalide

Abstract

A porous oxohalide, Fe₆Ca₂(SeO₃)₉Cl₄, has been synthesized by solid state reactions using concentrated HCl as the Cl-source. It crystallizes in the hexagonal space group P6₃/m with unit cell parameters a = 12.118(2) Å, c = 12.703(4) Å, Z = 2. The crystal structure is an open framework having one-dimensional channels extending along [001] that the chlorine atoms and lone pairs on Se⁴⁺ are facing. The channels in this framework structure are unusually large compared to other oxohalide compounds and also accessible to guest molecules. Water vapor sorption measurements show an uptake of 9 wt% at 293 K.