The molecular structure of Sr(NH 4 ) 2 [Fe(CN) 6 ]Á 2H 2 O, was determined by X-ray diffraction methods. It crystallizes in the orthorhombic Pnma space group with a = 13.1420(3), b = 14.1656(4), c = 7.3364(2) A ˚, and Z = 4. The structure was solved and refined. The iron(II) complex is located on a crystallographic inversion center with the metal in a nearly perfect octahedral environment [Fe-C bond distances from 1.919(4) to 1.939(4) A ˚]. The Sr(II) ion lies on a crystallographic mirror plane, sandwiched between two nearly square Archimedean anti-prism basis, angled 458 from each other. One base is formed by the two water molecules located on the mirror plane [SrÁÁÁOw distances of 2.741(4) and 2.636(4) A ˚] and by a pair of mirror-related cyanide N-atom [d(SrÁÁÁN) = 2.676(3) A ˚], the other one by two pairs of mirror-related cyanide nitrogen atoms [SrÁÁÁN distances of 2.649(3) and 2.640(4) A ˚] of neighboring [Fe(CN) 6 ] 4anions. The infrared absorption spectrum of the compound was also recorded and briefly discussed.

The ammonium, barium hexacyanoferrate(II) trihydrate, Ba(NH 4 ) 2 [Fe(CN) 6 ]Á3H 2 O, has been synthesized for the first time, was characterized by thermogravimetric and differential thermal analysis (TG-DTA), infrared (IR) and Raman spectroscopy and chemical analysis, and its crystal and molecular structures were determined by X-ray diffraction methods. The chemical composition was determined by assaying Ba(II) with EDTA, ammonia nitrogen with Nessler's reagent as indicator and Fe(II) using spectrophotometry with ortho-phenanthroline method. The hydration number was estimated by thermogravimetric analysis. The compound crystallizes in the trigonal R-3c space group. The ferrocyanide anion has an almost perfect octahedral shape with its Fe(II) ion in a crystallographic special position of point symmetry S 6 [d(Fe-C) = 1.912(2) A ˚, d(C-N) = 1.153(3) A ˚]. The barium, ammonium nitrogen and water oxygen atoms are also at lattice special positions with site symmetries D 3 , C 3 and C 2 , respectively. The thermal decomposition process was also studied using TG-DTA, and the products of decomposition were identified by IR spectroscopy. It proposes a mechanism of decomposition.

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