Chelate

Name:
Chelate
Detailed information:
The type of coordination compound in which a central metal ion such as Co²⁺, Ni²⁺, Cu²⁺, or Zn²⁺ is attached by coordinate links to two or more nonmetal atoms in the same molecule, called ligands. Heterocyclic rings are formed with the central (metal) atom as part of each ring. Ligands offering two groups for attachment to the metal are termed bidentate(two-toothed); three groups, tridentate; etc. A common chelating agent is ethylenediaminetetraacetic acid (EDTA). Nitrilotriacetic acid N(CH₂COOH)₃ and ethyleneglycol-bis(β-aminoethyl ether)-N,N-tetraacetic acid (HOOCCH₂)₂ NCH₂CH₂OCH₂CH₂OCH₂CH₂N(CH₂COOH)₂ are used in analytical chemical titrations and to remove ions from solutions and soils. Metal chelates are found in biological systems, e.g., the iron-binding porphyrin group of hemoglobin and the magnesium-binding chlorophyll of plants. Medicinally, metal chelates are used against Gram-positive bacteria, fungi, viruses, etc.See Ammine; Sequestration.