Crystal structure of calcium adipate monohydrate

Abstract

The crystal structure of calcium adipate monohydrate, Ca(C6H8O4)·H2O, has been determined by single crystal X-ray diffraction study. The crystals are triclinic witha=5.8990(3),b=6.7985(5),c=10.8212(6)A,α=78.999(5),β=81.831(5), and γ=82.971(5)°, space group P¯1,Z=2,V=419.65(8)A3,dm=1.59,dc=1.600 Mg m−3. The structure was refined by full-matrix least-squares techniques toR=0.040,Rw=0.058 for 1283 reflections withI≥3σ(I). Ca is coordinated to seven oxygen atoms and the coordination polyhedron is best described as pentagonal bipyramid. The coordinations of the two carboxylate groups in adipate ion are quite different. One carboxylate group binds 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 structure is highly polymeric, but with a layertype structure parallel to (001) with the hydrocarbon chains sandwiched between the polar regions consisting of Ca, carboxylate and water molecules.