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

The crystal structure of anhydrous tripotassium citrate, [K(3)(C(6)H(5)O(7))](n), has been solved and refined using laboratory X-ray powder diffraction data, and optimized using density functional techniques. The three unique potassium cations are 6-, 8-, and 6-coordinate (all irregular). The [KO(n)] coordination polyhedra share edges and corners to form a three-dimensional framework, with channels running parallel to the c axis. The only hydrogen bond is an intra­molecular one involving the hy­droxy group and the central carboxyl­ate group, with graph-set motif S(5).