FeEDTA

FeEDTA, or iron(III) ethylenediaminetetraacetate, is a coordination complex consisting of a ferric iron ion bound by the tetradentate EDTA ligand, forming [Fe(EDTA)]^- in its common ferric form. The EDTA ligand coordinates through four carboxylate oxygens and two amine nitrogens, creating a hexadentate, octahedral complex. The overall charge of ferric FeEDTA is typically -1; the exact oxidation state can vary with pH and coordinating conditions, with ferric form being more common in environmental and agricultural contexts.

Preparation typically involves complexation of iron salts (such as FeCl3) with disodium EDTA under controlled pH to deprotonate the ligand, yielding soluble FeEDTA in aqueous solution. The resulting chelate remains soluble across a broad pH range, helping to keep iron in solution where it would otherwise precipitate as Fe(OH)3 at neutral to alkaline pH.

Primary use is as a chelated iron source for fertilization. In agriculture and horticulture, FeEDTA is applied to soils or used in nutrient solutions to correct iron chlorosis in plants, particularly in calcareous or alkaline soils where iron solubility is limited. It is also employed in hydroponics and some foliar sprays.

Benefits include high stability and resistance to precipitation, enabling more consistent iron uptake by plants. Limitations include cost relative to inorganic iron salts and regulatory considerations for use in foods or environmental applications. FeEDTA is part of a broader family of EDTA chelates used to stabilize metals in solution and improve their bioavailability.