On the structure of 'potassium nitroprusside 0·8 hydrate'

Abstract

The crystal structure of the compound reported as K_2[Fe(CN)_5NO].0·8H_2O, potassium pentacyanonitrosylferrate hydrate (1/0·8), recently described and refined in the non-centrosymmetric space group Pna2_1 [orthorhombic; a = 30·000 (8), b = 11·272 (3), c = 16·053 (4) Å, Z = 20; Castellano, Rivero, Piro & Amalvy (1989). Acta Cryst. C45, 1207-1210], is properly described as centrosymmetric, space group Pnma. Refinement in Pnma shows that one of the K atoms is, instead, an Na atom and that three of the sites of the water molecules are partially occupied; the proper formulation of the compound is K_9Na[Fe(CN)_5NO]_5.nH_2O (n = 4·8).

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