Synthesis and crystal structure of Fe6Ca2(SeO3)9Cl4 a porous oxohalideElectronic supplementary information (ESI) available: Experimental details, crystal structure refinement parameters, bond valence sum (BVS) calculations, EDS-analysis data, sorption isotherms, PXRD-data. See DOI: 10.1039/c3dt50952d

A porous oxohalide, Fe 6 Ca 2 (SeO 3 ) 9 Cl 4 , has been synthesized by solid state reactions using concentrated HCl as the Cl-source. It crystallizes in the hexagonal space group P 6 3 / m with unit cell parameters a = 12.118(2) , c = 12.703(4) , Z = 2. The crystal structure is an open framework having one-dimensional channels extending along [001] that the chlorine atoms and lone pairs on Se 4+ 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. A new porous oxohalide, Fe 6 Ca 2 (SeO 3 ) 9 Cl 4 , is synthesized and characterized. The compound can be described as an open 3D framework where the Cl and the lone-pairs on Se 4+ are facing the channels, which are unusually large for an oxohalide, with a diameter of 6.4 .