Abstract

Single crystals of iron(II) tartrate hemi-pentahydrate, FeC₄H₄O₆·2.5H₂O, were grown by the gel method using silica gels. Differential scanning calorimetry, thermogravimetric-differential thermal analysis, and X-ray diffraction measurements were performed on the single crystals. The space group symmetry (orthorhombic P2₁2₁2₁) and structural parameters were determined at room temperature. The crystal structure consisted of slightly distorted FeO₆ octahedra, C₄H₄O₆ and H₂O molecules, C₄H₄O₆–Fe–C₄H₄O₆ chains jointed by Fe–O bonds, and O–H···O hydrogen-bonding frameworks between adjacent molecules. Weight losses due to thermal decomposition of the crystal were found to occur in the temperature range of 300–1060 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 black residue after decomposition was composed of triiron tetraoxide (Fe₃O₄) and carbon.

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