Effect of Zn Substitution on the Crystal Structure of (ND4)2[Cu[Zn](D2O6](SO4)2

The crystal structures of samples of deuterated ammonium copper(II) sulfate hexahydrate, in which a small fraction of the Cu2+ ions were replaced by Zn2+, have been determined. While the samples with lower Zn2+ concentrations have structures similar to that of the pure Cu2+ compound, the sample with 3.4% Zn2+ substitution has a structure similar to that observed for the unsubstituted compound at 1.5 kbar pressure, in which the long axis of the distorted Cu(D2O)6 2+ ion has switched from one pair of oxygen atoms to another pair.