A chelate compound is a type of coordination compound in which a central metal ion is bonded to a ligand, which is a molecule or ion capable of donating at least one electron pair to the central metal ion. The ligand forms a chelate ring with the metal ion, which is a closed loop of atoms or ions that coordinate to the metal ion.

Chelate compounds are characterized by their ability to form stable complexes with metal ions, which are important in biological processes, as well as in chemical reactions and industrial processes. The stability of chelate complexes arises from the multiple covalent bonds between the metal ion and the ligand, which form a stronger bond than a single coordination bond.

Chelate compounds have a wide range of applications, including as catalysts, in chemical synthesis, in agriculture and soil science, in pharmacology, and in the purification of metals. Some chelate compounds have been developed as drugs for the treatment of diseases such as cancer and arthritis.

Examples of chelate compounds include ethylenediaminetetraacetic acid (EDTA), which is widely used in analytical chemistry and in the treatment of heavy metal poisoning, and porphyrins, which are involved in many biological processes, such as oxygen transport and photosynthesis.