Single crystals of barium L-tartrate, BaC 4 H 4 O 6 , were grown at 308 K by a 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, P2 1 2 1 2 1 ) and structural parameters were determined at room temperature. The crystal structure consisted of BaO 9 polyhedra, C 4 H 4 O 6 molecules, and zig-zag hydrogen-bonded chains along the a-and c-axes linked by O-H···O and C-H···O hydrogen bonds between adjacent molecules. Weight losses due to thermal decomposition of BaC 4 H 4 O 6 occurred in the temperature range of 450-1530 K. We suggest that the evolution of 2H 2 , 2CO, CO, (1/2)O 2 , and O 2 gases caused the observed weight losses and that the decomposition product, barium monocarbide BaC, formed a residue in the vessel.

Single crystals of racemic strontium tartrate tetrahydrate, SrC 4 H 4 O 6 •4H 2 O, were grown at 308 K by a gel method using silica gel as the medium of growth. Differential scanning calorimetry, thermogravimetric-differential thermal analysis, and X-ray diffraction measurements were performed on the single crystals. The space group symmetry (triclinic P 1 __) and structural parameters were determined at room temperature. Weight losses due to thermal decomposition were found to occur in the temperature range of 370-1170 K, likely due to the evaporation of bound water molecules and the evolution of H 2 CO, (1/2)O 2 , and 2CO gases. The chalky white substance remaining in the vessel after decomposition was strontium oxide SrO. The crystal structure and thermal properties obtained were compared with those of racemic CaC 4 H 4 O 6 •4H 2 O reported previously.

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