Abstract
The crystal structure of dicesium hydrogen citrate, 2Cs+·C6H6O72-, has been solved using laboratory X-ray single-crystal diffraction data, refined using laboratory powder X-ray data, and optimized using density functional techniques. The Cs+ cation is nine-coordinate, with a bond-valence sum of 0.92 valence units. The CsO9 coordination polyhedra share edges and corners to form a three-dimensional framework. The citrate anion is located on a mirror plane. Its central hy-droxy/carboxyl-ate O-H⋯O hydrogen bond is short, and (unusually) inter-molecular. The centrosymmetric end-end carboxyl-ate hydrogen bond is exceptionally short (O⋯O = 2.416 Å) and strong. These hydrogen bonds contribute 16.5 and 21.7 kcal mol-1, respectively, to the crystal energy. The hydro-phobic methyl-ene groups occupy pockets in the framework.