The universal chelating ethylenediaminetetraacetic acid (EDTA) and its analogues has received check-wide application in various fields of science, technology and medicine. However, this ligand is characterized by low selectivity with respect to metals. By modifying this complexone scientists achieve greater selectivity of complex formation with respect to the different cations. Thus, the increase in the number of methylene units between the nitrogen atoms leads to a sharp increase in the dissociation constant of hydrogen penultimate stage (a betaine proton) pk3 and the relatively small increase in the dissociation constant of hydrogen latest betaine proton pk4. Gridchin S.N. and Pyreu D.F. [1] explain this phenomenon is a decrease in the mutual influence of iminodiacetate fragments to each other with increasing length of methylene bridge between the nitrogen atoms in the molecules of chelating agents. In addition, these same authors [2,3] suggest that the gap between betaine proton from EDTA (pk3 =6,16; pk4 =10,26[4]) is much lighter than those of counterparts as threemethylenediaminetetraacetic acid (TMDTA, pk3=8,02; pk4 =10,46 [4]), hexamethylenediaminetetraacetic acid (GMDTA, pk3=9,79; pk4 =10,81[4]). This fact is explained by the possibility of formation of the folded conformation of EDTA as a result of the mutual overlap of iminodiacetate chelating fragments with the closure of cross-links such as glycinate (-NH ... OOC-), leading to a weakening of NH bonds. Increasing the length of the hydrocarbon chain between the nitrogen atoms in GMDTA and TMDTA molecules prevents the convergence of the iminodiacetate fragments and the emergence of cross-hydrogen bonds. However, in the above described a number of chelating structural continuity is preserved due to the presence of two identical terminal iminodiacetate groups. For a more profound modification of the classical EDTA chelating we obtained the chelating containing terminal groups instead iminodiacetic fragments of aspartic acid [5]. This is a new class of chelating ethylenediaminedisuccinic acid (EDDS, pk4 =9,96 [6]) and hexamethylenediaminedisuccinic acid (GMDDS pk4 =10,24) [7]. Replacement of two acetic groups at each nitrogen atom to one succinic group provides an increase in biological activity of these chelating agents. Increasing the number of methylene units between the nitrogen atoms leads to an increase in the dissociation constant of the fourth proton from the betaine group. The feature of a new class of chelating agents, derivatives of succinic acid, is their environmental friendliness, as in nature, they quickly decompose into their constituent aminoacids and does not pollute the environment, in contrast to EDTA and its analogues.