Potassium tri­hydrogen 1,2,4,5-benzene­tetra­carboxyl­ate trihydrate

Colourless crystal of the title compound, K⁺·C₁₀H₅O₈⁻·3H₂O, were isolated under hydro­thermal conditions (423 K, 72 h). The structure consists of tri­hydrogen 1,2,4,5-benzene­tetra­carboxyl­ate (H₃btec⁻) anions, potassium cations and water of crystallization. Each K⁺ cation is seven-coordinated by four carboxyl­ate O atoms and three water O atoms. In turn, each H₃btec⁻ anion connects to four K⁺ cations and so an undulating layer forms. Adjacent layers are held together by hydrogen bonds to form a three-dimensional network. A short intramolecular hydrogen bond is found to exist in the H₃btec⁻ anions.