The crystal structure of calcium tartrate esahydrate, CaC4H4O6·6H2O, has been solved by the charge-flipping method from single-crystal X-ray diffraction data and refined to R = 0.021, based on 1700 unique observed diffractions. Salient crystallographic data are: a = 7.7390 (1), b = 12.8030 (2), c = 5.8290 (1) Å, Z = 2, and space group P2₁2₁2. During the refinement step it was possible to locate all H atoms by difference Fourier synthesis. The tartrate molecule has a (-)-gauche conformation and is coordinated to two calcium ions to form infinite chains along the a axis which alternate Ca polyhedra with tartrate molecules. The chains are interlinked by a three-dimensional network of hydrogen bonds from four water molecules surrounding the Ca ion, reinforced by hydrogen bonds from one interstitial water molecule. Micro-Raman and FT-IR spectroscopic data are provided.
Keywords: IR spectroscopy; calcium tartrate esahydrate; charge-flipping method; micro-Raman.