ANALYSIS OF SPECIALTIES OF CRYSTAL STRUCTURE FOR NON-­CHELATE CONFORMATIONS OF ETHYLENE-DIAMINETETRAACETIC ACID AND ITS SALTS WITH ALKALI AND ALKALINE EARTH METALS

In the present study, crystal structures of non-chelating EDTA molecules and their non-chelation salts in a zwitterionic state, along with EDTA-chelates alkali alkaline earth metals, were searched overviewed. 25 EDTA, zwitterions ethylenediammonium-diacetate diacetic acid HOOC-CH2-(-OOC-CH2-)NH+-CH2-CH2-NH+(-CH2-COO-)-CH2-COOH (ethylenediammonium-tetraace­tic (HOOC-CH2-)2NH+-CH2-CH2-NH+(-CH2-COOH)2, ethylenediammonium-acetate triacetic (HOOC-CH2-)2NH+-CH2-CH2-NH+(-CH2-COO-)-CH2-COOH, ethylenediammonium-tetraacetate (-OOC-CH2-)2NH+-CH2-CH2-NH+(-CH2-COO-)2 counterions), as well 17 types metal ions (Li+, Na+, K+, Rb+) (Mg2+, Ca2+, Sr2+, Ba2+) analyzed using data from Cambridge Crystallographic Data Center (CCDC). Each intramolecular contact distance between nitrogen oxygen atoms (NH+···O) has been examined found to be around 2.7 Å. Investigation on distribution NH+··· NH+-distances non-chelated thereof also revealed that bulky counterion certain solvent correspond change packing, they influenced conformers mo­lecules among gauche form anti form. existing crystalline metals various coordination numbers (CN) denticity (к) anions are displayed; CN 5 9, tri- hexadentate fashions. Intramolecular N···O N···N distances ion radii except for case Sr-EDTA chelate, probably due differences packings addition number counterions molecules. The its have gathered herein, which contributes further understanding exploring applications hereafter.