Abstract

Copper(II) L-tartrate trihydrate, L-CuC₄H₄O₆·3H₂O, and copper(II) DL-tartrate dihydrate, DL-CuC₄H₄O₆·2H₂O, crystals were grown at room temperature by the gel method using silica gels as the growth medium. Differential scanning calorimetry, thermogravimetric-differential thermal analysis, and X-ray diffraction measurements were performed on both crystals. The space group symmetries (monoclinic P2₁ and P2₁/c) and structural parameters of the crystals were determined at room temperature and at 114 K. Both structures consisted of slightly distorted CuO₆ octahedra, C₄H₄O₆ and H₂O molecules, C₄H₄O₆–Cu–C₄H₄O₆ chains linked by Cu–O bonds, and O–H–O hydrogen-bonding frameworks between adjacent molecules. Weight losses due to thermal decomposition of the crystals were found to occur in the temperature range of 300–1250 K. We inferred that the weight losses were caused by the evaporation of bound water molecules and the evolution of H₂CO, CO, and O₂ gases from C₄H₄O₆ molecules, and that the residual reddish-brown substance left in the vessels after decomposition was copper(I) oxide (Cu₂O).

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