High Quality Content by WIKIPEDIA articles! Iminodiacetic acid, HN(CH2CO2H)2, often abbreviated to IDA, is an dicarboxylic acid amine. The iminodiacetate anion can act as a tridentate ligand to form a metal complex with two, fused, five membered chelate rings. The proton on the nitrogen atom can be replaced by a carbon atom of a polymer to create an ion-exchange resin, such as chelex 100.