Crystal structures of two isostructural compounds: a second polymorph of dipotassium hydrogen citrate, K2HC6H5O7, and potassium rubidium hydrogen citrate, KRbHC6H5O7

Title Crystal structures of two isostructural compounds: a second polymorph of dipotassium hydrogen citrate, K2HC6H5O7, and potassium rubidium hydrogen citrate, KRbHC6H5O7
Authors Gonzalez D, Golab JT, Cigler AJ, Kaduk JA.
Journal Acta Crystallogr C Struct Chem
DOI 10.1107/S2053229620008281
Abstract

The crystal structures of a new polymorph of dipotassium hydrogen citrate, 2K+·HC6H5O72-, and potassium rubidium hydrogen citrate, K+·Rb+·HC6H5O72-, have been solved and refined using laboratory powder X-ray diffraction and optimized using density functional techniques. In the new polymorph of the dipotassium salt, KO7 and KO8 coordination polyhedra share corners and edges to form a three-dimensional framework with channels parallel to the a axis and [111]. The hydrophobic methylene groups face each other in the channels. The un-ionized carboxylic acid group forms a strong charge-assisted hydrogen bond to the central ionized carboxylate group. The hydroxy group forms an intermolecular hydrogen bond to a different central carboxylate group. In the potassium rubidium salt, the K+ and Rb+ cations are disordered over two sites, in approximately 0.72:0.28 and 0.28:0.72 ratios. KO8 and RbO9 coordination polyhedra share corners and edges to form a three-dimensional framework with channels parallel to the a axis. The un-ionized carboxylic acid group forms a strong charge-assisted hydrogen bond to an ionized carboxylate group. The hydroxy group forms an intermolecular hydrogen bond to the central carboxylate group. Density functional theory (DFT) calculations on the ordered cation structures suggest that interchange of K+ and Rb+ at the two cation sites changes the energy insignificantly.

Citation Gonzalez D, Golab JT, Cigler AJ, Kaduk JA..Crystal structures of two isostructural compounds: a second polymorph of dipotassium hydrogen citrate, K2HC6H5O7, and potassium rubidium hydrogen citrate, KRbHC6H5O7. 2020 Jul 1;76(Pt 7):706-715. doi: 10.1107/S2053229620008281

Related Elements

Potassium

19 K 39.098300000 Potassium

Elemental PotassiumSee more Potassium products. Potassium (atomic symbol: K, atomic number: 19) is a Block S, Group 1, Period 4 element with an atomic weight of 39.0983. The number of electrons in each of Potassium's shells is [2, 8, 8, 1] and its electron configuration is [Ar] 4s1. The potassium atom has a radius of 227.2 pm and a Van der Waals radius of 275 pm. Potassium was discovered and first isolated by Sir Humphrey Davy in 1807. Potassium is the seventh most abundant element on earth. It is one of the most reactive and electropositive of all metals and rapidly oxidizes. As with other alkali metals, potassium decomposes in water with the evolution of hydrogen because of its reacts violently with water, it only occurs in nature in ionic salts.Potassium Bohr Model In its elemental form, potassium has a silvery gray metallic appearance, but its compounds (such as potassium hydroxide) are more frequently used in industrial and chemical applications. The origin of the element's name comes from the English word 'potash,' meaning pot ashes, and the Arabic word qali, which means alkali. The symbol K originates from the Latin word kalium.

Rubidium

37 Rb 85.467800000 Rubidium

See more Rubidium products. Rubidium (atomic symbol: Rb, atomic number: 37) is a Block S, Group 1, Period 5 element with an atomic weight of 5.4678. The number of electrons in each of Rubidium's shells is [2, 8, 18, 8, 1] and its electron configuration is [Kr] 5s1. The rubidium atom has a radius of 248 pm and a Van der Waals radius of 303 pm. Rubidium Bohr ModelRubidium is highly reactive, with properties similar to other Group 1 alkali metals, e.g., rapid oxidation in air. In its elemental form, rubidium has a gray white appearance. Rubidium is found in the minerals lepidolite, leucite, pollucite, carnallite, and zinnwaldite as well as some potassium minerals. Rubidium was discovered by Robert Bunsen and Gustav Kirchhoff in 1861 and was first isolated by George de Hevesy. The name Rubidium, originates from the Latin word rubidus, meaning "dark or deepest red."

Publish your research on the American Elements website