Structural and Thermal Studies on Racemic PbC4H4O6•2H2O Single Crystal

Single crystals of racemic lead tartrate dihydrate, PbC4H4O6·2H2O, were grown at 308 K by the gel method using silica gel as the growth medium. Differential scanning calorimetry, thermogravimetric-differential thermal analysis, and X-ray diffraction measurements were performed on the single crystals. The space group symmetry (orthorhombic Pbca) and the structural parameters were determined at room temperature. The structure consisted of PbO8 polyhedra, C4H4O6 molecules, two independent H2O molecules, and zig-zag hydrogen-bonded chains along the a- and b-axes linked by O–H···O hydrogen bonds between adjacent molecules. Weight losses due to thermal decomposition of racemic PbC4H4O6·2H2O occurred in the temperature range of 300–1600 K. We suggested that the weight losses in the ranges of 300–900 K and 900–1600 K were caused by the evolution of gases from 2H2O and C4H4O5, and the evaporation of PbO, respectively.