K2MnII2(H2O)2C2O4(HPO3)2: A New 2D Manganese(II) Oxalatophosphite with Double-Layered Honeycomb Sheets Stabilized by Potassium Ions

Abstract

A novel 2D metal oxalatophosphite K2MnII2(H2O)2C2O4(HPO3)2 (KMnCP) was hydrothermally synthesized and characterized. The hexagonal morphology and crystal growth faces of KMnCP were predicted by Bravais–Friedel–Donnay–Harker (BFDH) theory. Single crystal X-ray diffraction analysis revealed that the compound displays a unique double layered structure constructed from Mn(H2O)(HPO3) single layers linked by oxalate ligands, where the potassium levels interrupt the 3D connectivity through the organic bridges. Moreover, in order to classify this archetype a crystallochemical revision of the metal oxalatophoshites with anionic frameworks has been carried out. Several Secondary Building Units (SBUs) formed by metal-phosphite substructures and different roles of de oxalate bridges have been observed, what has led to propose a new structural classification for this kind of materials with common features between the classic inorganic metal phosphates and coordination polymers. Finally, the thermal, spectroscopic and magnetic properties together with the electronic structure of the studied compound are discussed