title: Sodium dipotassium citrate, NaK2C6H5O7.
abstract: The crystal structure of sodium dipotassium citrate, Na(+)·2K(+)·C6H5O7 (3-), has been solved and refined using laboratory X-ray powder diffraction data, and optimized using density functional techniques. The Na(+) and one of the K(+) cations are six-coordinate, with bond-valence sums of 1.13 and 0.92 valence units, respectively, while another crystallographically independent K(+) cation is seven-coordinate with a bond-valence sum of 1.20. The [KO6] and [KO7] polyhedra share edges and corners to form layers perpendicular to the b axis. The distorted [NaO6] octa-hedra share edges to form chains along the a axis. The result is a three-dimensional network. The only O-H⋯O hydrogen bond is an intra-molecular one between the hy-droxy group and a terminal carboxyl-ate group.
authors.affiliation: Atlantic International University, Honolulu HI , USA.
authors.forename: Alagappa
authors.initials: A
authors.lastname: Rammohan
authors.affiliation: Illinois Institute of Technology, Chicago IL , USA.
authors.forename: James A
authors.initials: JA
authors.lastname: Kaduk
keywords: citrate; density functional theory; potassium; powder diffraction; sodium