Crystal and molecular structure of the “asymmetric” ethylenediamine-N,N-di-3-propionic acid monohydrate

A new complexing agent the “asymmetric” ethylenediamine-N,N-di-3-propionic acid (as.EDDP) is obtained. The crystal structure of the new compound is determined by single-crystal X-ray diffraction. C8H16N2O4·H2O crystals are monoclinic; space group P21/c, a = 12.7416(4) Å, b = 6.5470(2) Å, c = 12.1908(4) Å, β = 93.100(1)°, Z = 4, ρx = 1.454 mg/m3, and R1 (I > 2.0σ(I)) = 0.0326. In the solid form, the as.EDDP molecule has a double betaine structure: [graphic not available: see fulltext] The intramolecular hydrogen bonds with the betaine proton of the tertiary nitrogen atom are formed with the participation of one oxygen atom of the carboxyl group of each 3-propionic fragment, which forms two N(1)-H(1N)-bonded six-membered H-cycles. The intermolecular hydrogen bonds are formed between the three hydrogen atoms of the protonated primary nitrogen atom and the oxygen atoms of the 3-propionic fragments of three other as.EDDP molecules. The water molecule participates in the formation of intermolecular hydrogen bonds with the oxygen atom of one carboxyl group of the molecule.