Crystal structure of trirubidium citrate from laboratory X-ray powder diffraction data and DFT comparison

The crystal structure of trirubidium citrate, 3Rb(+)·C(6)H(5)O(7) (3−), has been solved and refined using laboratory X-ray powder diffraction data, and optimized using density functional techniques. The two independent Rb(+) cations are seven- and eight-coordinate, with bond-valence sums of 0.99 and 0.92 valence units. The coordination polyhedra share edges and corners to form a three-dimensional framework. The only hydrogen bond is an intra­molecular one between the hy­droxy group and the central carboxyl­ate, with graph set S(5). The hydro­phobic methyl­ene groups lie in pockets in the framework.