Calcium tartrate esahydrate, CaC_4H_4O_6·6H_2O: a structural and spectroscopic study

摘要

The crystal structure of calcium tartrate esahydrate, CaC_4H_4O_6·6H_2O, 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) A °, Z = 2, and space group P2_12_12. 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.