The five-membered rings are slightly strained. EDDS’s six donor sites form both five- and six-membered chelate rings around the metal ion: two NC2OFe rings, two NC3OFe rings, and one C2N2Fe ring.
The structure of the five-membered rings is slightly imperfect. EDDS’s six attachment points create both five- and six-ringed arrangements around the metal center: two NC2OFe rings, two NC3OFe rings, and one C2N2Fe ring.