AMINOGUANIDINIUM(2- A CO-PRODUCT OF PREPARING THE FERROELECTRIC ANHYDROUS SALT() HEXAFLUOROZIRCONATE MONOHYDRATE )

Preparation of anhydrous aminoguanidinium(2+) hexafluorozirconate, CN4 H8ZrF6, shown previously to satisfy the structural criteria for ferroe lectricity [Abrahams et al. (1996). Acta Cryst. B52, 806-809], general ly results in the co-formation of a series of related fluorozirconates . The structure of the monohydrate salt, one of the coproducts, has be en redetermined to improve understanding of the preparation pathway, l ocate the H atoms and compare corresponding atom positions [Gerasimenk o er al. (1989). Koord. Khim. 15, 130-135]. The positions of the H ato ms were not established in the latter study. All 16 H atoms in the two symmetry-independent CN4H8(2+) ions are now located and refined, with R-1 = 0.0299 and S = 1.119. Both independent water molecules are diso rdered. Normal probability analysis reveals uncompensated error and/or underestimated uncertainty associated with ten non-H-atom position co ordinates. The relative concentrations of HF, CN4H7Cl and H2ZrF6 are a mong the major variables controlling the formation of the related fluo rozirconates.