The Crystal Structures of the Potassium Nitroprusside 2.5 and 0.8 Hydrates

E. E. CASTELLANO; B. E. RIVERO; O. E. PIRO; J. I. AMALVY

Acta Cryst. C

IUCr

Año: 1989 vol. 45 p. 1207 - 1210

Abstract. Potassium pentacyanonitrosylferrate hydrate (1/2.5), K2[Fe(CN)sNO].2.5H20, Mr = 339.18, monoclinic, P21/n (No. 14), a = 10.054(4), b = 24.510(5), c = 11.018(6) A, beta =109.60(4) ° , V= 2558 (3) A^3, Z = 8, Dm = 1.75, D = l.762 g.cm^-3, MoKalpha radiation, lamda = 0.71073 A,  mu(MoKalpha) = 18 cm^-1, F(000) = 1352. Potassium pentacyanonitrosylferrate hydrate (1/0.8), K2[Fe(CN)5NO]. 0.8H20 , Mr=311.98, orthorhombic, Pna21 (No. 33), a = 30.000(8), b = 11.272(3), c = 16.053(4) A, V = 5428 (2) A^3, Z = 20, Dm = 1.909 g. cm^-3, MoKalpha radiation, lamda = 0.71073 A, mu(MoKalpha) = 21 cm^-l, F(000) = 3108. Both structures were solved by the heavy-atom technique and refined anisotropically to R factors 0.040 and 0.059, from 2805 and 3436 (I > 3sigma(I)) independent reflections, respectively. In both structures the water molecules are not involved in strong hydrogen bonds. The low specificity of these interactions is probably responsible for the occurrence of the three different hydrates reported [Amalvy, Varetti, Aymonino, Castellano, Piro & Punte (1986). J.Crystallogr. Spectrosc. Res. 16, 537-555].