Crystal structure of potassium hydrogen phthalate revisited

Abstract

The present study provides new insight into the structure of potassium hydrogen phthalate 1. The single crystal X-ray structure of 1 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 c 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 a axis. The structure of 1 is stabilised by π∙∙∙π stacking interactions. A comparative study of the structures of alkali metal hydrogen phthalates is described.