THE CRYSTAL-STRUCTURE OF CALCIUM GLUTARATE MONOHYDRATE

The crystal structure of calcium glutarate monohydrate, Ca(C5H6O4). H2O, has been determined by single crystal X-ray diffraction. The crystals(1) are orthorhombic with a = 6.805(1) Angstrom, b = 18.486(2) Angstrom, c = 5.884(1) Angstrom, space group P2(1)2(1)2(1), Z = 4, V = 740.1(2) Angstrom(3), d(m) = 1.69, and d(c) = 1.688 Mg m(-3). The structure was refined by full-matrix least-squares techniques to R = 0.019, R(w) = 0.026, for 1198 reflections with I greater than or equal to 3 sigma(I). The absolute configuration was determined. Ca is coordinated to seven oxygen atoms and the coordination polyhedron is best described as pentagonal bipyramid. One carboxylate group of the glutarate ion is bonded to three different Ca ions, forming a four-membered chelate ring with one Ca ion and unidentate bridge bonds to two other Ca ions. The other carboxylate group links to two Ca ions through unidentate bonds. The Ca-glutarate chains are packed approximately parallel to the b-axis, with the hydrocarbon chains sandwiched between the polar regions consisting of the Ca and carboxylate ions and water molecules.