Crystal structure of potassium hydrogen phthalate revisited

Abstract

The present study provides new insight into the structure of potassium hydrogen phthalate <strong>1</strong>. The single crystal X-ray structure of <strong>1</strong> consists of a crystallographically independent potassium cation and a unique hydrogen phthalate anion. The µ₄-heptadentate binding mode of the unique hydrogen phthalate ligand organizes the K⁺ ions into a layer resulting in a two-dimensional (2D) coordination polymer. As a result parallel chains of face-sharing {KO₇} polyhedra extending along <em>c</em> are formed. The parallel chains are flanked on either side by hydrogen phthalate wings and are interlinked by vertex sharing of three polyhedra to extend the connectivity along <em>a</em> axis. The structure of <strong>1</strong> is stabilised by π∙∙∙π stacking interactions. A comparative study of the structures of alkali metal hydrogen phthalates is described.