Heteroligand complexes of some rare earth metals with CDTA and unsaturated dicarboxylic acids |
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| Affiliation: | 1. Ecological and Environmental Protection Department, Linyi Vocational University Of Science and Technology, Linyi, Shandong 27600, PR China;2. School of Materials Engineering, Changshu Insititute of Technology, Changshu, Jiangsu 215500, PR China;1. N.S. Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, Leninsky Prosp. 31, 119991 GSP-1 Moscow, Russian Federation;2. A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilova Str. 28, 119991 Moscow, Russian Federation;3. P.N. Lebedev Physical Institute, Russian Academy of Sciences, Leninsky Prosp. 53, 119991 Moscow, Russian Federation;4. Vavilov Institute of General Genetics, Russian Academy of Sciences, Gubkina, 3, 119333 Moscow, Russian Federation;5. Lomonosov Moscow State University, Dept. of Chemistry, Leninskie Gory 1/3, Moscow 119991, Russian Federation;6. National Medical Research Center of Phthisiopulmonology and Infection Diseases, 22 Parts’ezda St., 50, Ekaterinburg 620039, Russian Federation;7. Postovsky Institute of Organic Synthesis, Ural Branch of the Russian Academy of Sciences, S. Kovalevskoy Str., 22, Ekaterinburg 620137, Russian Federation |
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| Abstract: | Potentiometric evidence has been cited for the formation of heteroligand 1:1:1, ternary and 1:1:1:1, quaternary species in the systems M(III)-CDTA-CCA/MIA and M(III)-CDTA-CCA-MIA, respectively (M(III) = La(III), Pr(III), Nd(III), Gd(III) or Dy(III); CDTA = cyclohexanediaminetetra-acetic acid; CCA = citraconic acid and MIA = maleic acid). The protonated mixed ligand complexes, existing in the low pH range, appear to undergo deprotonation resulting in the formation of normal chelates at comparatively higher pH. The formation constants log KMLL′ and log KMLL′L″, respectively, for ternary and quaternary species, formed by simultaneous addition of the ligands to the metal ion and deprotonation constants,-log KAH, for protonated ternary species have been evaluated at 27 ± 1°C and ionic concentration (μ) = 0.1 M KNO3. The order of relative stabilities is La(III) < Pr(III) < Nd(III) < Gd(III) < Dy(III). |
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