Redetermination of sulfatotris(thiourea)zinc(II)

In the title compound, [Zn(SO4)(CH4N2S)(3)], the Zn2+ cation is coordinated in a tetrahedral geometry by one O atom from a sulfate anion and the S atoms from three thiourea ligands. There are weak N-H center dot center dot center dot O and N-H center dot center dot center dot S hydrogen bonds in the structure, some of which are bifurcated. The same crystal has also been investigated at 110 K, below a reported phase transition at 120 K. No change in the space group below 120 K was observed. On the other hand, the differences between the fractional coordinates of the corresponding atoms in the determinations at 292 and 110 K are as large as about 0.007 for the non-H atoms. Differential scanning calorimetry did not detect reproducible anomalies in the interval 93-503 K up to the melting point.