The Crystal and Molecular Structure of Strontium Nitroprusside Dihydrate

E. E. CASTELLANO; O. E. PIRO; A. D. PODJARNY; B. E. RIVERO; P. J. AYMONINO; J. H. LESK; E. L. VARETTI

Acta Cryst. B

IUCr

Año: 1978 vol. 34 p. 2673 - 2676

Sr[Fe(CN)sNO].2H20, obtained by dehydration of a single crystal of the tetrahydrate, crystallizes in the orthorhombic system, space group Ccmm, with a = 19.4 (3), b = 7.5 (1), c = 8.3 (1) A, Z = 4. The sample showed disorder around b and only an hOl layer of reflections was collected. The structure was solved by the heavy-atom method and refined by constrained least-squares calculations in projection to R = 13.2% for 43 reflections. Ions and water molecules are in special positions mm. Comparison with the tetrahydrate shows the lack of the two equivalent water molecules which are presumed to form strong hydrogen bonds in this last compound. It shows also the relocation of the ions into mm sites which causes the change from monoclinic to orthorhombic symmetry. The proposed structure gives support to TGA-DTA and infrared data, which will be published elsewhere.