Growth, crystalline perfection and characterization of hexaaquanickel(II) dipotassium tetrahydrogen tetra-o-phthalate tetrahydrate crystals

Synthesis, growth, structure and characterization of potassium lithium hydrogen phthalate mixed crystals

Mixed crystals of lithium-incorporated potassium hydrogen phthalate were grown by the slow evaporation solution growth technique from an aqueous solution containing equimolar quantities of potassium hydrogen phthalate (KHP) and lithium carbonate.

Dirubidium hexaaquacobalt(II) tetrakis(hydrogen phthalate) tetrahydrate and coordination modes of the hydrogen phthalate anion

The title compound, Rb₂[Co(H₂O)₆](C₈H₅O₄)₄·4H₂O, consists of nearly regular octahedral [Co(H₂O)₆]²⁺ cations with the CoII cations on the inversion centre (special position 2a), Rb⁺ cations, hydrogen phthalate (Hpht⁻) anions and disordered water molecules. The Rb⁺ cation is surrounded by nine O atoms from Hpht⁻ anions and water molecules, with a strongly deformed pentagonal-bipyramidal geometry and one apex split into three positions. The crystal packing is governed by numerous hydrogen bonds involving all water molecules and Hpht⁻) anions. In this way, layers parallel to the ab plane are formed, with the aromatic rings of the Hpht⁻ anions esentially directed along the c axis. While Hpht⁻ anions form the outer part of the layers, disordered water molecules and Rb⁺ cations alternate with [Co(H₂O)₆]²⁺ cations in the inner parts. The only interactions between the layers are van der Waals forces between the atoms of the aromatic rings. A search of the Cambridge Structural Database for coordination modes and types of hydrogen-bonding interaction of the Hpht⁻ anion showed that, when uncoordinated Hpht⁻ anions are present, compounds with intermolecular hydrogen bonds are more numerous than compounds with intramolecular hydrogen bonds. For coordinated Hpht⁻ anions, chelating and bridging anions are almost equally common, while monodentate anions are relatively scarce. The same coordination modes appear for Hpht⁻ anions with or without intramolecular hydrogen bonds, although intramolecular hydrogen bonds are less common.