oxalatebased

Oxalate-based compounds refer to materials and substances in which the oxalate dianion (C2O4^2−) forms a defining structural unit. In inorganic and materials chemistry, oxalate often acts as a ligand binding to metal centers, typically as a bidentate donor, and it can also bridge between metals to build extended networks. The term covers salts, coordination complexes, and metal–organic frameworks in which oxalate links act as connectors between metal nodes.

Coordination modes and structure: Oxalate can coordinate in several ways—chelation, bridging, or mixed chelating-bridging modes—enabling discrete clusters, chains, sheets, or three-dimensional frameworks. Its relatively small size and multiple oxygen donors promote stable metal–oxygen bonds, contributing to thermal stability and tunable porosity in oxalate-based materials. Thermal decomposition often releases carbon monoxide and carbon dioxide, yielding metal oxides.

Occurrence and examples: In nature, calcium oxalate crystals accumulate in many plants and can form in the human body, contributing to kidney stones. Classic inorganic oxalates include copper(II) oxalate, iron(II) oxalate, and calcium oxalate, as well as soluble salts such as sodium oxalate. These species are widely used as reagents and pigment precursors.

Applications and synthesis: Oxalate-based compounds are prepared by reacting metal salts with oxalic acid or oxalate sources. They serve as pigments, precursors to metal oxides, and versatile ligands in coordination chemistry. In materials science, oxalate-linked networks and composites are explored for catalysis, sensing, and gas storage, while oxalate ligands enable assembly of predictable architectures.

Safety and health: Oxalates can be toxic in high amounts; dietary oxalates have been associated with stone formation in susceptible individuals. Handling of oxalate salts requires standard laboratory safety practices, including appropriate protective equipment and proper waste disposal.