CRYSTAL-STRUCTURES OF SIMPLE MONOCLINIC AND ORTHORHOMBIC POLYTYPES OF TRIPOTASSIUM HEXACYANOFERRATE(III)

The room-temperature (295 K) crystal structures of potassium ferricyanide, K3 [Fe(CN)6], have been determined for the simplest monoclinic (a reinvestigation) and orthorhombic polytypes by single- crystal X-ray diffraction. The monoclinic form is P21/c, a 7-047(3), b 10-400(3), c 8 384(3) Å, β 107-29(3)°, Z 2. The iron atoms lie on special positions with symmetry I. In the orthorhombic form, Pnca, a 13-422(6), b 10-396(4), 8-381(4) Å, Z4, the iron atoms now lie on special positions with symmetry 2 (parallel to c). Residuals are 0-036 and 0-048 for 1232 and 855 ‘observed’ reflections respectively. © 1978 Australian Journal of Chemistry.