Diammonium potassium citrate, (NH4)2KC6H5O7

The crystal structure of di­ammonium potassium citrate, 2NH(4) (+)·K(+)·C(6)H(5)O(7) (3−), has been solved and refined using laboratory X-ray powder diffraction data and optimized using density functional theory. The KO(7) coordination polyhedra are isolated. The ammonium cations and the hydro­phobic methyl­ene sides of the citrate anions occupy the spaces between the coordination polyhedra. Each hydrogen atom of the ammonium ions acts as a donor in a charge-assisted N—H⋯O, N—H⋯(O,O) or N—H⋯(O,O,O) hydrogen bond. There is an intra­molecular O—H⋯O hydrogen bond in the citrate anion between the hydroxide group and one of the terminal carboxyl­ate groups. [Image: see text