Complexons (polyaminopolycarboxylic acids) are among the most widely used polydentate ligands. Interest in complexones, derivatives of dicarboxylic acids and, in particular, derivatives of succinic acid (SCDA), has increased in last years, which is associated with the development of simple and accessible methods for their synthesis and the presence of a number of specific practically useful properties.
The most important method for the synthesis of CPAA is based on the interaction of maleic acid with various compounds containing a primary or secondary amino group. If aliphatic monoaminomonocarboxylic acids are taken as such compounds, mixed-type complexons (MCTs) are obtained, and when maleic acid reacts with ammonia, iminodisuccinic acid (IDAS), the simplest representative of MCAC, is obtained. Syntheses take place under mild conditions, without requiring high temperatures or pressure, and are characterized by fairly high yields.
Speaking about the practical application of CPAC, we can highlight the following areas.
1. Production of building materials. The use of CPACs in this area is based on their pronounced ability to slow down the hydration process of binders (cement, concrete, gypsum, etc.). This property is important in itself, since it allows you to regulate the setting speed of binders, and in the production of cellular concrete it also allows you to save significant amounts of cement. The most effective in this regard are IDYAK and KST.
2. Water-soluble fluxes for soft soldering. Such fluxes are especially relevant for the electrical and radio engineering industries, in which the technology for producing printed circuit boards requires the mandatory removal of flux residues from the finished product. Typically, rosin fluxes used for soldering are removed only with alcohol-acetone mixtures, which is extremely inconvenient due to the fire hazard of this procedure, while fluxes based on some KPYAK are washed off with water.
3. Antianemic and antichlorotic drugs for agriculture. It was found that complexes of ions of a number of 3d transition metals (Cu 2+, Zn 2+, Co 2+, etc.) with CPAC have high biological activity. This made it possible to create on their basis effective antianemic drugs for the prevention and treatment of nutritional anemia of fur-bearing animals (primarily minks) in fur farming and antichlorosis drugs for the prevention and treatment of chlorosis of fruit and berry crops (especially grapes) grown on carbonate soils ( southern regions countries) and for this reason prone to chlorosis. It is also important to note that due to the ability to undergo exhaustive destruction in conditions environment, CPYAC are environmentally friendly products.
In addition to the above areas, the presence of anti-corrosion activity in CPACs has been shown, and the possibility of their use in chemical analysis, medicine and some other areas has been shown. Methods for obtaining CPYAC and their practical application V various areas are protected by the authors of this report by numerous copyright certificates and patents.
Bibliographic link
Nikolsky V.M., Pchelkin P.E., Sharov S.V., Knyazeva N.E., Gorelov I.P. SYNTHESIS AND APPLICATION OF COMPLEXONES DERIVATIVES OF SUCCINE ACID IN INDUSTRY AND AGRICULTURE // Advances modern natural science. – 2004. – No. 2. – P. 71-71;URL: http://natural-sciences.ru/ru/article/view?id=12285 (access date: 01/05/2020). We bring to your attention magazines published by the publishing house "Academy of Natural Sciences"
COMPLEXONES, organic compounds containing N, S or P atoms capable of coordination, as well as carboxyl, phosphonic and other acid groups and forming stable intra-complex compounds with metal cations - chelates. The term “complexones” was introduced in 1945 by the Swiss chemist G. Schwarzenbach to designate aminopolycarboxylic acids exhibiting the properties of polydentate ligands.
Complexons - colorless crystalline substances, usually soluble in water, aqueous solutions alkalis and acids, insoluble in ethanol and other organic solvents; dissociate in the pH range 2-14. In aqueous solutions with cations of transition d- and f-elements, alkaline earth and some alkali metals, complexons form stable intracomplex compounds - complexonates (mono- and polynuclear, medium, acidic, hydroxo complexonates, etc.). Complexonates contain several chelate rings, which makes such compounds highly stable.
To solve a wide range practical problems More than two hundred complexones with various properties are used. The complexing properties of complexons depend on the structure of their molecules. Thus, an increase in the number of methylene groups between N atoms in the alkylenediamine fragment >N(CH 2) n N< или между атомами N и кислотными группами снижает устойчивость комплексонатов многих металлов, кроме Pd(II), Cd(II), Cu(II), Hg(II) и Ag(I), то есть приводит к повышению избирательности комплексонов. На избирательность взаимодействия комплексонов с ионами металлов также влияет наличие в молекулах комплексонов объёмных заместителей и таких функциональных групп, как -ОН, -SH, -NH 2 , -РО 3 Н 2 , -AsO 3 Н 2 .
The most widely used complexons are nitrilotriacetic acid (complexon I), ethylenediaminetetraacetic acid (EDTA, complexon II) and its disodium salt (trilon B, complexon III), as well as diethylenetriaminepentaacetic acid, a number of phosphoryl-containing complexons - nitrilotrimethylenephosphonic acid, ethylenacid, new acid. Phosphoryl-containing complexons form complexonates in a wide range of pH values, including in strongly acidic and strongly alkaline environments; their complexonates with Fe(III), Al(III) and Be(II) are insoluble in water.
Complexons are used in the oil and gas industry to inhibit scale deposition during joint production, field collection, transportation and preparation of oil of different grades, during the drilling and casing of oil and gas wells. Complexons are used as titrants in complexometry in the determination of ions of many metals, as well as reagents for the separation and isolation of metals, water softeners, to prevent the formation (and dissolution) of deposits (for example, with increased water hardness) on the surface of heating equipment, as additives , slowing down the hardening of cement and gypsum, stabilizers for food and cosmetics, components of detergents, fixatives in photography, electrolytes (instead of cyanide) in electroplating.
Complexones and complexonates are generally non-toxic and are quickly eliminated from the body. In combination with the high complexing ability of complexons, this ensured the use of complexones and complexonates of some metals in agriculture for the prevention and treatment of anemia in animals (for example, minks, piglets, calves) and chlorosis of plants (mainly grapes, citrus and fruit crops). In medicine, complexons are used to remove toxic and radioactive metals from the body in case of poisoning, as regulators of calcium metabolism in the body, in oncology, in the treatment of certain allergic diseases, and in diagnostics.
Lit.: Prilibil R. Complexons in chemical analysis. 2nd ed. M., 1960; Schwarzenbach G., Flashka G. Complexometric titration. M., 1970; Moskvin V.D. et al. The use of complexones in the oil industry // Journal of the All-Russian Chemical Society named after D.I. Mendeleev. 1984. T. 29. No. 3; Gorelov I.P. et al. Complexons - derivatives of dicarboxylic acids // Chemistry in agriculture. 1987. No. 1; Dyatlova N. M., Temkina V. Ya., Popov K. I. Complexons and metal complexonates. M., 1988; Gorelov I.P. et al. Iminodisuccinic acid as a hydration retarder of lime binder // Construction materials. 2004. No. 5.
We carry out all types of student work
ThesisDshrbonic acids.13. Chapter p. research methods. 32. Experimental part. Page Chapter sh. technique and experimental procedure. 40. The results of the study are presented in four chapters. The first two chapters (literature review) are devoted to analog complexones and the research methods used in the work. Two chapters of the experimental part contain data on the synthesis and study of complex formation...
Study of complex formation of rare earth and other elements with some complexons, derivatives of diaminocyclohexane isomers and dicarboxylic acids (essay, coursework, diploma, test)
LITERATURE REVIEW
CHAPTER I. ABOUT COMPLEXONES, DERIVATIVES OF DIAMINOCYCLOHEXANE ISOMERS AND COMPLEXONES, DERIVATIVES
DERBONIC ACIDS.13
1.1. Synthesis of complexones.-. 13
1.2. Acid dissociation constants. 14,
1.3. Complexes of ASH and magnesium. . . 16
1.4. Complexes d - transitional and some other elements.. 19
1.5. REE complexes.23
CHAPTER P. RESEARCH METHODS.32
2.1. pH-metric titration method. 32
2.1.1. Determination of acid dissociation constants for tetrabasic acids.. J32
2.1.2. Potentiometric method for determining the stability constants of complexes. 33
2.2. Indirect potentiometric method using a stationary mercury electrode.-.34
2.3. Indirect potentiometric method using a dropping copper amalgam electrode. 36
2.4. Spectrographic method. 38
EXPERIMENTAL PART
CHAPTER III. TECHNIQUES AND EXPERIMENTAL METHODS. 40
3.1. Synthesis of KPDK-DCG.40
3.1.1. Synthesis of trans-1,2-diaminocyclohexane-N N-dimalonic acid... 41
3.1.2. Synthesis of cis-1,3-diaminocyclohexane - N, N"-dimalonic acid.42
3.1.3. Synthesis of trans-I,4-diaminocyclohexane-N,N-dimalonic acid. . 43
3.1.4. Synthesis of cis-1,4-diaminocyclohexane-N, N-dimalonic acid. . . 43
3.1.5. Synthesis of trans-I,2-diaminocyclohexane-N,N"-disuccinic acid.44
3.1.6. Physical properties KPDK-DCG. 45
3.2. Initial substances and devices used. 46
3.3. Mathematical processing of experimental results.. 47
The results of the study are presented in four chapters. The first two chapters (literature review) are devoted to analog complexones and the research methods used in the work. Two chapters of the experimental part contain data on the synthesis and study of the complexing ability of new complexons.
LITERATURE REVIEW
G L, A B, A I.
ABOUT COMPLEXONES DERIVATIVES OF DSHINOCYCLO ISOMERS
HEXANES AND DICARBOXYLE DERIVATIVE COMPLEXONES
Other jobs
Thesis
The purpose of this work is to study the individual stages of growth and aggregation of calcium sulfate hemihydrate crystals, which is necessary to find ways to control the formation of the microtexture of a solid, as well as to create a physical and mathematical model of the crystallization process, without which it is impossible to create optimal technological processes. In this work we used a complex...
Thesis
Based on the research results, new extraction methods for the extraction and separation of rare earth elements from sulfate solutions have been developed. Mixtures of available and widely used reagents - alkylphosphoric acids and primary amines - are recommended as extractants. The developed methods have been tested in large laboratory tests for the extraction of rare earth elements from process solutions obtained by sulfuric acid...
Thesis
In the 1:2 complexes of palladium (1G) with alanine and serine Pd (AlaXAla")Cl and Pd (Ser)(Ser")Cl, one amino acid molecule is a monodentate neutral ligand due to the coordination of the amino group nitrogen with palladium (II). The anion of the second molecule is a bdenate cyclic ligand due to palladium(II) coordination of the nitrogen of the amino group and the oxygen of the carboxyl group. In complex compounds...
Thesis
Two representatives of oximes were used as ligands: salicylaldoxime (aromatic benzenoid system) and 1,2-naphthoquinone-1-monooxime (aromatic quinoid system). In addition to the main task - the study of electrophilic reactions for intrasphere ligands - additional tasks were set: To establish for the obtained platinum complexes the nature of the electronic distribution and type...
Scientific novelty The possibility of creating metal-containing nanoparticles consisting of metals of various natures (Fe, Co, N1, Zn, Ce, Ccl, Pc1, Ag, Mo) or their inorganic compounds, localized on the surface of the DNA. Hybrid composite materials have been created, consisting of a LDPE matrix, in the volume of which DND microgranules decorated with nanoparticles of inorganic...
Thesis
Scientific novelty. Practical significance. Conditions have been developed for the targeted synthesis of thin-film lead titanate structures on silicon with ferroelectric properties that can be used for functional electronics devices. Approbation of work. The main results of the work were presented and reported at the Proceedings of the Third International Conference Single Crystal Growth...
The developed synthesis methods can be used to obtain a variety of trifluoroacetate complexes. The study of sublimation processes and thermolysis products of trifluoroacetate complexes makes it possible to use these substances in various technological processes. The results of X-ray diffraction studies make a fundamental contribution to inorganic and coordination chemistry...
Thesis
Current direction when studying complex equilibrium systems containing several metal ions, one of which is paramagnetic, the most reliable method for studying such systems is a combination of proton magnetic relaxation methods and mathematical modeling. The use of this set of methods largely determines the relevance of this work" when studying...
Frolov Yu. V., Pivkina A. N. Fractal structure and features of energy release (combustion) processes in heterogeneous systems // FGV. 1997. T. 33. No. 5. P. 3−19. Tsunoda R., Ozawa T., Ando J. Ozone treatment of coal- and coffee grounds-based active carbons: water vapor adsorption and surface fractal micropores // J. Coll. Int. Sci. 1998. V. 205. P. 265−270. Rong H., Xuchang X., Changhe C., Hongli F...
Thesis
The physical and physicochemical properties of alcoholates are generally determined by the action of two opposing trends - the desire of the metal to increase its coordination number by forming bridging bonds with alkoxo groups and the counteracting effect - spatial hindrances that arise in the case of branched alkyl groups. The consequence of this is a wide range...
Thesis
The T-X phase diagrams of polythermal sections, liquidus surfaces and isothermal sections of these systems constructed for the first time will certainly find application in connection with the theoretical and practical development of methods for the synthesis of new compounds, and can also be used as reference material. On the thermoelectric figure of merit of compounds with the tetradymite structure (Bi^Se^, Bi^Te^...
Copyright OJSC "CDB "BIBKOM" & LLC "Agency Kniga-Service" As a manuscript Semenova Maria Gennadievna HOMOLIGAND AND HETEROLIGAND COORDINATION COMPOUNDS OF COBALT(II) AND NICKEL(II) WITH MONOAMINE CARBOXYMETHYL COMPLEXONES AND SAT DICARBONIC COMPLEXONES MI ACIDS IN AQUEOUS SOLUTIONS 02.00.01 – inorganic chemistry ABSTRACT of the dissertation for the degree of Candidate of Chemical Sciences Kazan - 2011 Copyright JSC Central Design Bureau BIBKOM & LLC Book-Service Agency 2 The work was carried out at the State Educational Institution of Higher Professional Education "Udmurt State University" Scientific supervisor: Doctor of Chemical Sciences, Professor Kornev Viktor Ivanovich Official opponents: Doctor of Chemical Sciences, Professor Valentin Konstantinovich Polovnyak Candidate of Chemical Sciences, Professor Valentin Vasilievich Sentemov Leading organization: Federal State Autonomous Educational Institution of Higher Professional Education "Kazan (Volga Region) State University" Defense will take place on May 31, 2011 at 1400 o'clock at a meeting of the dissertation council D 212.080.03 at the Kazan State Technological University at the address: 420015, Kazan, st. Karl Marx, 68 (meeting room of the Academic Council). The dissertation can be found at scientific library Kazan State Technological University. The abstract was sent out on “__” April 2011. Scientific secretary of the dissertation council Tretyakova A.Ya. Copyright OJSC Central Design Bureau BIBKOM & LLC Kniga-Service Agency 3 GENERAL CHARACTERISTICS OF THE WORK Relevance of the topic. Research into the patterns of formation of heteroligand complexes in equilibrium systems is one of the most important problems of coordination chemistry, which is inextricably linked with the implementation of innovative chemical technologies. The study of complex formation of cobalt(II) and nickel(II) with complexones and dicarboxylic acids in aqueous solutions is very useful for justification and modeling chemical processes in multicomponent systems. The synthetic availability and wide possibilities for modifying these ligands create great potential for creating complex-forming compositions with the required set of properties based on them. The information available in the literature on coordination compounds of cobalt(II) and nickel(II) with the studied ligands is poorly systematized and incomplete for a number of ligands. There is virtually no information on heteroligand complex formation. Considering that Co(II) and Ni(II) complexes with the reagents under consideration have not been sufficiently studied, and the results obtained are very contradictory, the study of ionic equilibria in these systems and under the same experimental conditions is very relevant. Only taking into account all types of interactions can give an adequate picture of the state of equilibrium in complex multicomponent systems. In light of the above considerations, the relevance of targeted and systematic studies of the processes of complexation of cobalt(II) and nickel(II) salts with complexones and dicarboxylic acids for coordination chemistry seems obvious and significant. Goals of work. Identification of equilibria and identification of features of the formation of homo- and heteroligand complexes of cobalt(II) and nickel(II) with monoamine carboxymethyl complexones and saturated dicarboxylic acids in aqueous solutions. To achieve the intended goal, the following tasks were set: to experimentally study the acid-base properties of the ligands under study, as well as the conditions for the formation of homo- and heteroligand complexes of cobalt(II) and nickel(II) in a wide range of pH values and reagent concentrations; determine the stoichiometry of complexes in binary and ternary systems; carry out mathematical modeling of complex formation processes taking into account the completeness of all equilibria realized in the systems under study; Copyright OJSC Central Design Bureau BIBKOM & LLC Kniga-Service Agency 4 establish the range of pH values for the existence of complexes and the proportion of their accumulation; calculate the stability constants of the found complexes; determine the coproportionation constants of reactions and draw a conclusion about the compatibility of ligands in the coordination sphere of metal cations. Scientific novelty. For the first time, a systematic study of homo- and heteroligand complexes of cobalt(II) and nickel(II) with monoamine carboxymethyl complexones: iminodiacetic (IDA, H2Ida), 2-hydroxyethyliminodiacetic (HEIDA, H2Heida), nitrilothiacetic (NTA, H3Nta), methylglycine diacetic (MGDA, H3Mgda) acids and dicarboxylic acids of the limit series: oxalic (H2Ox), malonic (H2Mal) and succinic (H2Suc). Interaction in solutions is considered from the perspective of the polycomponent nature of the systems under study, which determines the presence of diverse competing reactions in the solution. The results of a quantitative description of homogeneous equilibria in systems containing cobalt(II) and nickel(II) salts, as well as monoamine complexons and dicarboxylic acids are new. For the first time, the stoichiometry of heteroligand complexes was identified, the equilibrium constants of reactions and the stability constants of Co(II) and Ni(II) complexes with the studied ligands were determined. Practical value. A well-founded approach to the study of complex formation of cobalt(II) and nickel(II) with monoamine carboxymethyl complexones and dicarboxylic acids of the limiting series is proposed using various physicochemical research methods, which can be used to solve problems of coordination chemistry to establish stoichiometry, equilibrium constants of reactions and stability constants of homo- and heteroligand complexes of these metals. A comprehensive analysis of the studied systems on the stoichiometry and thermodynamic stability of cobalt(II) and nickel(II) complexes made it possible to establish some regularities between the structure of chelates and their complexing properties. This information may be useful when developing quantitative methods determination and masking of the studied cations using complexing compositions based on complexones and dicarboxylic acids. The information obtained can be used to create technological solutions with specified properties and good performance characteristics. Copyright JSC "CDB "BIBKOM" & LLC "Agency Kniga-Service" 5 The found values of the equilibrium constants of reactions can be taken as reference. The data obtained in the work is useful for using it in the educational process. The main provisions submitted for defense: results of studying the acid-base properties, protolytic equilibria and forms of existence of the studied ligands; patterns of formation of homo- and heteroligand complexes of cobalt(II) and nickel(II) with monoamine carboxymethyl complexones and dicarboxylic acids under conditions of a variety of competing interactions; results of mathematical modeling of equilibria in complex multicomponent systems based on spectrophotometry and potentiometry data; influence various factors on complex formation processes in the systems under study; stoichiometry of complexes, equilibrium constants of reactions, coproportionation constants and stability constants of the resulting complexes, pH ranges of their formation and existence, as well as the influence of ligand concentrations on the fraction of accumulation of complexes. Personal contribution of the author. The author analyzed the state of the problem at the time of the start of the research, formulated the goal, carried out the experimental work, took part in the development of the theoretical foundations of the subject of research, discussed the results obtained and presented them for publication. The main conclusions on the work carried out were formulated by the dissertation author. Approbation of work. The main results of the dissertation work were reported at the XXIV International Chugaev Conference on Coordination Connections (St. Petersburg, 2009), the All-Russian Conference " Chemical analysis"(Moscow - Klyazma, 2008), IX Russian University-Academic Scientific and Practical Conference (Izhevsk, 2008), as well as at the annual final conferences of the Udmurt State University. Publications. The materials of the dissertation work are presented in 14 publications, including 6 abstracts of reports at All-Russian and International scientific conferences and 8 articles, among which 5 were published in journals included in the List of leading peer-reviewed scientific journals and publications recommended by the Higher Attestation Commission of the Ministry of Education and Science of Russia. Copyright JSC Central Design Bureau BIBKOM & LLC Book-Service Agency 6 Structure and scope of the dissertation. The dissertation consists of an introduction, a literature review, an experimental part, a discussion of the results, conclusions and a list of references. The material of the work is presented on 168 pages, including 47 figures and 13 tables. The list of cited literature contains 208 titles of works by domestic and foreign authors. MAIN CONTENT OF THE WORK The study of complex formation processes was carried out using spectrophotometric and potentiometric methods. The optical density of solutions was measured on spectrophotometers SF-26 and SF-56 using a specially made Teflon cuvette with quartz glass and an absorbing layer thickness of 5 cm. Such a cuvette allows you to simultaneously measure the pH value and optical density of the solution. All A = f(pH) curves were obtained by spectrophotometric titration. Mathematical processing of the results was carried out using the CPESSP program. The basis for the study of complex formation in binary and ternary systems was the change in the shape of the absorption spectra and the optical density of solutions of Co(II) and Ni(II) perchlorates in the presence of complexones and dicarboxylic acids. In addition, we constructed theoretical models of complexation for ternary systems without taking into account heteroligand complexation. When comparing the theoretical dependences A = f(pH) with the experimental ones, deviations associated with the processes of formation of heteroligand complexes were identified. The working wavelengths chosen were 500 and 520 nm for Co(II) compounds and 400 and 590 nm for Ni(II), at which the intrinsic absorption of ligands at different pH is insignificant, and complex compounds exhibit a significant hyperchromic effect. When identifying equilibria, three constants of monomeric hydrolysis were taken into account for each of the metals. The dissociation constants of complexones and dicarboxylic acids used in the work are presented in Table 1. Monoamine carboxymethyl complexones can be represented as derivatives of iminodiacetic acid with general formula H R + N CH2COO– CH2COOH where R: –H (IDA), –CH2CH2OH (HEIDA), –CH2COOH –CH(CH3)COOH (MGDA). (NTA) and Copyright JSC Central Design Bureau BIBKOM & LLC Kniga-Service Agency 7 The dicarboxylic acids of the limiting series used in the work can be represented by the general formula Cn H2n(COOH)2 (H2Dik). The nature of the dependence A = f(pH) for the M(II)–H2Dik systems showed that in each of these systems, as a rule, three complexes +, , 2– are formed, except for the M(II)–H2Suc system in which bisdicarboxylates are not formed . We were unable to establish the nature of the equilibria in the Co(II)–H2Ox system, since at all pH values poorly soluble precipitates of cobalt(II) oxalates precipitate, which makes photometry of the solution impossible. Table 1. Protonation and dissociation constants of complexones and dicarboxylic acids at I = 0.1 (NaClO4) and T = 20±2°С HjL H2Ida H2 Heida H3Nta H3Mgda* H2Ox H2Mal H2Suc lgKb,1 pK1,a pK2,a pK3,a 1.82 2.61 9.34 1.60 2.20 8.73 1.25 1.95 3.05 10.2 1.10 1.89 2.49 9.73 1.54 4.10 2.73 5.34 4.00 5.24 * Established in this work Protonated complexes are formed in a strongly acidic environment in all systems. Increasing the pH of solutions leads to deprotonation and the formation of medium metal dicarboxylates. The complex is formed in area 3.0< рН < 8.0 и уже при соотношении 1: 1 имеет долю накопления 73%. Содержание комплекса 2– равно 14, 88 и 100% для 1: 1, 1: 2 и 1: 5 соответственно в области 3.0 < рН < 10.1. Аналогичные процессы протекают в системах M(II)–H2Mal. Увеличение концентрации малоновой кислоты сказывается на доле накопления комплекса , так для соотношения 1: 1 α = 60 % (6.3 < рН < 8.5), а для 1: 10 α = 72 % (2.0 < рН < 4.4). Содержание в растворе комплекса 2– возрастает c 64% до 91% для соотношений 1: 10 и 1: 50 (6.0 < рН 9.5). Максимальные доли накопления комплекса и 2– при оптимальных значениях рН составляют 70 и 80% для соотношения концентраций 1: 10 и 54 и 96% для 1: 50. Увеличение концентрации янтарной кислоты в системах M(II)–H2Suc способствует возрастанию долей накопления комплексов [МSuc] и [МHSuc]+ и смещению области их формирования в более кислую среду. Например, доли накопления комплекса при соотношении концентраций 1: 1, 1: 10 и 1: 40 соответственно равны 16, 68 и 90 %. Содержание комплексов Copyright ОАО «ЦКБ «БИБКОМ» & ООО «Aгентство Kнига-Cервис» 8 + и при соотношении 1: 50 равно 54% (рНопт. = 3.9) и 97% (рНопт. = 7.7) соответственно. Константы устойчивости дикарбоксилатов Co(II) и Ni(II), рассчитанные методом последовательных итераций приведены в таблице 2. Полученные нами величины хорошо согласуются с рядом литературных источников. Математическая обработка кривых A = f(pH) и α = f(pH) проведенная путем последовательного рассмотрения моделей равновесий с участием Co(II) и Ni(II) и моноаминных комплексонов (HxComp) показала, что во всех исследованных двойных системах типа M(II)–HxComp образуется несколько комплексов. В качестве примера на рис. 1 представлены кривые A = f(pH) для систем Co(II)–H2Heida (а) и Ni(II)–H2Heida (б). А а А б 0.5 0.4 3 0.4 3 4 0.3 4 5 0.3 1 0.2 0.2 0.1 0 5 2 0.1 0 2 4 6 8 10 рН 0 2 4 6 8 10 рН Рис. 1. Зависимость оптической плотности растворов от рН для кобальта(II) (1) и никеля(II) (2) и их комплексов с H2 Heida при соотношении компонентов 1: 1 (3), 1: 2 (4), 1: 5 (5), ССо2+ = 6∙10–3, СNi2+ = 8∙10–3 моль/дм3, λ = 520 (а), 400 нм (б). Методами насыщения и изомолярных серий установлено мольное соотношение компонентов в комплексонатах в зависимости от кислотности среды равное 1: 1 и 1: 2. Мольный состав комплексов подтвержден также методом математического моделирования. При эквимолярном соотношении компонентов стопроцентная доля накопления наблюдается только для комплексов – и –, а для комплексов , , и значения αmax равны 82, 98, 85 и 99% соответственно. В слабокислой среде монокомплексонаты Co(II) и Ni(II) присоединяют второй анион комплексона, образуя средние бискомплексонаты 2(1–x). При двукратном избытке комплексона максимальные доли накопления комплексов 2–, 2– и Copyright ОАО «ЦКБ «БИБКОМ» & ООО «Aгентство Kнига-Cервис» 9 4– находятся в пределах 88 – 99% для области 8.6 < рН < 11.6. В данном интервале рН накапливаются и комплексы 4– и 4–, для которых αmax достигает 56 и 72% соответственно. Одновременно с бискомплексонатами металлов в двойных системах, за исключением систем M(II)–H2Ida в щелочной среде образуется также гидроксокомплексы 1–x. Константы устойчивости комплексонатов Co(II) и Ni(II) представлены в таблице 2. Таблица 2. Области значений рН существования и константы устойчивости дикарбоксилатов и комплексонатов кобальта(II) и никеля(II) при I = 0.1 и Т = 20 ± 2°С Комплекс Области рН существования lg Комплекс Области рН существования lg + 2– + 2– + 2– 2– – – 4– 2– – – – 0.4–5.5 >1.9 >3.2 2.0–7.0 >3.6 2.4–12.0 >4.6 1.4–12.0 >4.8 >8.8 >1.0 >5.1 >9.8 5.46* 4.75* 6.91* 5.18 ± 0.06 2.97 ± 0.08 4.51 ± 0.08 6.29 ± 0.0 9 1.60 ± 0.10 6.81 ± 0.08 11.69 ± 0.16 8.16 ± 0.14 12.28 ± 0.66 11.88 ± 0.37 10.10 ± 0.76 13.50 ± 0.12 12.50 ± 0.09 + 2– + 2– + 2– 2– – – 4– 2– 0.0–3.2 >0.2 >1.2 0.3–5.5 >1.9 >3.3 1.9–7.1 >2.8 1.2–5.9 >2.1 1.0–12.0 >3.7 >10.0 >0.8 >4.3 >9.6 6.30 ± 0.08 5.35 ± 0.08 9.25 ± 0.10 6.70 ± 0.07 3.50 ± 0.09 5.30 ± 0.0 7 6.39 ± 0.10 1.95 ± 0.08 8.44 ± 0.05 14.80 ± 0.08 9.33 ± 0.05 14.20 ± 0.06 12.05 ± 0.11 11.38 ± 0.76 16.34 ± 0.05 13.95 ± 0.09 – 4– 2– >1.1 >7.2 >10.5 >1.0 >7.0 >9.3 1 2.95 ± 0.13 16.29 ± 0.24 15.85 ± 0.58 11.27 ± 0.13 – 14.03 ± 0.35 4– 13.08 ± 0.72 2– *Literary data Complexation processes in ternary systems also depend on the concentration of reagents and the acidity of the medium. For the formation of heteroligand complexes, the concentration of each of the ligands must be no less than their concentration in binary systems with a maximum fraction of accumulation of the homoligand complex. Copyright JSC Central Design Bureau BIBKOM & LLC Kniga-Service Agency 10 It has been established that in all ternary systems heteroligand complexes with a molar ratio of 1: 1: 1 and 1: 2: 1 are formed, with the exception of the M(II)–H2Ida systems –H2Dik, in which only 1:1:1 complexes are formed. Evidence of the existence of heteroligand complexes was the fact that the theoretical curves A = f(pH) calculated without taking into account heteroligand complex formation differ markedly from the experimental curves (Fig. 2.) A 0.3 Fig. . Fig. 2. Dependence of the optical density of solutions on pH for nickel(II) (1) and its complexes with H2Ida (2), H2Ox (3), H2Ida + H2Ox (4, 6), the curve calculated without taking into account heteroligand complexes (5), at component ratio 1: 5 (2), 1: 2 (3), 1: 2: 2 (4, 5), 1: 2: 5 (6); СNi2+ = 8∙10–3 mol/dm3. 2 0.2 4 6 5 0.1 3 1 0 0 2 4 6 8 10 pH In the M(II)–H2Ida–H2Dik systems, the formation of three types of complexes is possible –, 2– and 3–. Moreover, if the system contains oxalic acid, then Co(II) and Ni(II) oxalates act as structure-setting particles. In ternary systems containing H2Mal or H2Suc, the role of the primary ligand is played by iminodiacetates of these metals. Protonated complexes are formed only in the M(II)–H2Ida–H2Ox systems. Complexes – and – are formed in a strongly acidic environment and in the range of 2.5< рН < 3.0 их содержание достигает 21 и 51% соответственно (для соотношения 1: 2: 2). В слабокислой среде кислые комплексы депротонируются с образованием средних гетеролигандных комплексов состава 2– и 2–, максимальные доли накопления которых при рН = 6.5 – 6.6 соответствеено равны 96 и 85% (для 1: 2: 2). При рН > 10.0 complex 2– is hydrolyzed to form 3–. Similar processes occur in the M(II)–H2Ida–H2Mal systems. Complexes 2– and 2– have maximum accumulation fractions of 80 and 64% (for 1: 2: 10 and pH = 6.4). In an alkaline environment, the middle complexes are converted into hydroxo complexes of type 3–. Copyright JSC Central Design Bureau BIBKOM & LLC Kniga-Service Agency 11 Equilibria in the M(II)–H2Ida–H2Suc systems are strongly shifted towards Co(II) and Ni(II) iminodiacetates, even at large excesses of H2Suc. Thus, at a ratio of 1: 2: 50, in these systems only medium complexes of composition 2– and 2– are formed, the content of which in the solution is 60 and 53%, respectively (pH = 6.4). In the M(II)–H2Heida–H2Dik systems, the formation of four types of complexes is possible: –, 2–, 4– and 3–. A protonated heteroligand complex was established for both metals studied and for all ligands except the – complex. The middle complexes 2– and 4– are formed in slightly acidic and alkaline media with a maximum accumulation fraction of 72 and 68% at pH = 5.8 and 9.5, respectively (for 1: 2: 1). Nickel(II) oxalates in GEID solution form heteroligand complexes of composition –, 2– and 4–; the αmax values for these complexes are 23, 85 and 60% for optimal pH values of 2.0, 7.0 and 10.0, respectively. The completeness of the formation of heteroligand complexes in the M(II)–H2Heida–H2Mal system strongly depends on the H2Mal concentration. For example, in the Ni(II)–H2Heida–H2Mal system at a concentration ratio of 1: 2: 10, the maximum fractions of accumulation of complexes –, 2– and 4– are 46, 65 and 11% for pH 4.0, 6.0 and 10.5, respectively. With an increase in the concentration of malonic acid by 50 times, the accumulation fractions of these complexes at the same pH values increase to 76, 84 and 31%, respectively. In the Co(II)–H2 Heida–H2Mal system with a component ratio of 1: 2: 75, the following transformations take place: – αmax = 85%, pH = 3.4 – H+ 2– αmax = 96%, pH = 6.5 + Heida2– 4– αmax = 52%, pH = 9.8 Heteroligand complexes in the M(II)–H2 Heida–H2Suc systems are formed only with large excesses of succinic acid. Thus, for a ratio of 1: 2: 100, the maximum fractions of accumulation of complexes –, 2– and 4– are equal to 67 (pH = 4.8), 78 (pH = 6.4) and 75% (pH = 9.0), and for complexes –, 2– and 4– – 4 (pH = 4.6), 39 (pH = 6.0) and 6% (pH = 9.0 ÷ 13.0), respectively. In the M(II)–H3Nta–H2Dik systems, similar processes occur. In the presence of oxalic acid in an acidic environment, the solution is dominated by Co(II) and Ni(II) oxalates with a small content of 2– complexes. Closer to the neutral environment, medium heteroligand complexes 3– and 3– are formed with a maximum accumulation fraction of 78 and Copyright JSC Central Design Bureau BIBKOM & LLC Agency Kniga-Service 12 90% for pH = 6. 9 and 6.4 respectively. In an alkaline environment with an excess of NTA, the reaction proceeds in two directions with the formation of complexes 4– and 6–. The latter accumulate in large quantities, for example, the share of accumulation of complex 6– reaches 82% at pH = 7.0. The fractional distribution of complexes in the Co(II)–H3Nta–H2Mal system is shown in Fig. 3. α, % g c a 80 b g b 60 b c c a 40 b g a c d d c g b c 20 a b a a 0 + рН = 2.3 – рН = 3.2 2– рН = 3.8 2– рН = 6.8 4– pH = 10.5 6– pH = 10.5 Fig. 3. Proportions of accumulation of complexes at different pH values and different ratios of components: 1: 2: 5 (a), 1: 2: 20 (b), 1: 2: 40 (c), 1: 2: 80 (d) c system Co(II)–H3Nta–H2Mal. In the M(II)–H3Nta–H2Suc systems, the structure-setting ligand is H3Nta, and succinic acid plays the role of an additional ligand. An increase in the concentration of H2Suc leads to an increase in the proportion of accumulation of heteroligand complexes. Thus, an increase in the content of succinic acid from 0.0 to 0.12 mol/dm3 leads to an increase in the α value of complex 3– from 47 to 76%, while the content of protonated complex 2– increases from 34 to 63% (at pH = 4.3). The fractional ratio of complexes 3– and 2– changes in approximately the same ratio. In an alkaline environment, complexes 3– add another H3Nta molecule, and complexes of composition 6– are formed. The maximum fraction of accumulation of complex 6– is 43% at pH = 10.3 for the ratio 1: 2: 40. For the corresponding nickel(II) complex α = 44% at pH = 10.0, for the ratio 1: 2: 50. At pH > 10.0 the average heteroligand complexes are hydrolyzed to form hydroxo complexes of composition 4–. Copyright JSC Central Design Bureau BIBKOM & LLC Kniga-Service Agency 13 Homoligand complexes in the M(II)–H3Nta–H2Suc systems are represented only by – and 4–, no succinate complexes are detected. The stability constants of heteroligand complexes are presented in Table 3. Table 3. Stability constants of heteroligand complexes of cobalt (II) and nickel(II) with complexones and dicarboxylic acids for I = 0.1 (NaClO4) and T = 20±2°С Complex H2Ox H2Mal H2Suc – 2– 3– – 2– 3– – 2– 4– 3– – 2– 4– 3– 2– 3– 6– 4– 2– 3– 6– 4– 2– 3– 4– 2– 3– 6 – 4– 14.90 ± 0.19 11.27 ± 0.66 – 17.38 ± 0.11 13.09 ± 0.10 15.97 ± 1.74 – 12.39 ± 0.15 16.28 ± 0.61 15.70 ± 0.28 16.92 ± 0.12 13.47 ± 0 .18 16.50 ± 0.20 15.39 ± 0.23 15.53 ± 0.31 12.31 ± 0.22 – 14.95 ± 0.09 17.60 ± 0.56 14.75 ± 0.24 18.98 ± 0.05 17.70 ± 0.09 16.99 ± 0.26 13.36 ± 0.73 15.73 ± 0.14 18.43 ± 0.28 15.90 ± 0.25 19.21 ± 0. 19 – – 9.20 ± 0.27 10.40 ± 0.17 – 10. 76 ± 0.38 – 15.58 ± 0.28 11.07 ± 0.43 14.07 ± 1.09 14.18 ± 0.52 16.15 ± 0.19 11.36 ± 0.63 14.73 ± 1.30 12.17 ± 0.68 16.49 ± 0.34 11.8 0 ± 0.17 15.25 ± 0.04 14.95 ± 0.09 16.93 ± 0.46 13.20 ± 0.45 17.50 ± 0.16 15.85 ± 0.09 16.93 ± 0.47 11.92 ± 0.71 15.28 ± 0.94 – 13.93 ± 0.76 17.26 ± 0.72 16.65 ± 0.35 – 7.82 ± 0.66 – – 9.61 ± 0.67 – 14.73 ± 0.43 9.49 ± 1.65 13.53 ±1.55 13.24 ±1.51 13.83 ± 0.79 9.77 ± 0.26 13.44 ± 0.47 – 16.84 ± 0.34 11.65 ± 0.17 15.50 ± 0.10 15.05 ± 0.03 17.79 ± 0.34 12.85 ± 0.18 17.03 ± 0.06 16.50 ± 0.13 – 11.41 ± 0.34 15.13 ± 0.95 – 12.93 ± 0.42 – 16.84 ± 0.73 Copyright JSC Central Design Bureau BIBKOM & Kniga-Service Agency LLC 14 In the M(II)–H3Mgda–H2Dik systems, the formation of four types of complexes is also possible: 2–, 3–, 6– and 4–. However, not all of these complexes are formed in individual systems. Both metals form protonated complexes in solutions of oxalic acid, and Co(II) also in solutions of malonic acid. The share of accumulation of these complexes is not large and, as a rule, does not exceed 10%. Only for complex 2– αmax = 21% at pH = 4.0 and component ratio 1: 2: 50. The content of complex 3– increases significantly with increasing concentration of oxalic acid. With a twofold excess of H2Ox, the share of accumulation of this complex is 43% in the region of 6.0< рН < 9.0, а при десятикратном она увеличивается до 80%. При рН >10.0, even at a high concentration of oxalate ions, this complex is hydrolyzed to form 4–. Nickel(II) complex 3– is formed in region 6.4< рН < 7.9 и для соотношения компонентов 1: 2: 10 доля его накопления составляет 96%. При рН >7.0, another average heteroligand complex of composition 6– is formed in solution (α = 67% at pHHotp. = 11.3). A further increase in the H2Ox concentration has virtually no effect on the α value for these complexes. At a concentration ratio of 1: 2: 25, the accumulation fractions of complexes 3– and 6– are 97 and 68%, respectively. The structure-setting particle in the M(II)–H3Mgda–H2Ox systems is oxalic acid. In Fig. Figure 4 shows the curves α = f(pH) and A = f(pH), which characterize the state of equilibrium in the M(II)–H3Mgda–H2Mal systems. Heteroligand complexation in the M(II)–H3Mgda–H2Suc systems also strongly depends on the concentration of succinic acid. With a tenfold excess of H2Suc, heteroligand complexes are not formed in these systems. With a concentration ratio of 1: 2: 25 in the range of 6.5< рН < 9.0 образуются комплексы 3– (αmax = 10%) и 3– (αmax = 8%)/ Пятидесятикратный избыток янтарной кислоты увеличивает содержание этих комплексов до 15 – 16%. При стократном избытке H2Suc области значений рН существования комплексов 3– значительно расширяются, а максимальная доля накопления их возрастает приблизительно до 28 – 30%. Следует отметить, что для образования гетеролигандного комплекса в растворе необходимо определенное геометрическое подобие структур реагирующих гомолигандных комплексов, причем структура свойственная гомолигандному комплексу стабилизируется в гетеролигандном. Copyright ОАО «ЦКБ «БИБКОМ» & ООО «Aгентство Kнига-Cервис» 15 α 1.0 а А 2 4 1 6 3 0 2 7 6 8 б 2 10 A 4 1 0.3 0.2 5 4 1.0 0.4 9 0.5 α 0.2 6 0.5 8 7 0.1 рН 0.1 3 0 2 4 6 8 10 рН Рис. 4. Зависимость долей накопления комплексов (α) и оптической плотности растворов (A) от рН в системах Co(II)–H3Mgda–H2Mal (а) и Ni(II)–H3Mgda–H2Mal (б) для соотношения 1: 2: 50: экспериментальная кривая A = f(pH) (1), М2+ (2), [МHMal]+ (3), – (4), 2– (5), 3– (6), 4– (7), 6– (8), 4– (9); СCo2+ = 3∙10–3, СNi2+ = 4∙10–3 моль/дм3. Одним из факторов, определяющих стехиометрию и устойчивость гетеролигандных комплексов является совместимость лиганда в координационной сфере катиона металла. Мерой совместимости служит константа сопропорционирования Kd, характеризующая равновесия вида: 2(1–x) + 4– 2 x– В случае Kd > 1 (or logKd > 0) ligands in the coordination sphere are compatible. For our set of heteroligand complexes, the Kd value (Kd = β2111/ βMComp2βMDik2) is always greater than unity, which indicates the compatibility of the ligands in the coordination sphere of Co(II) and Ni(II). In addition, in all cases, the logβ111 value of the heteroligand complex exceeds the geometric mean of the logβ values of the corresponding bicomplexes, which also indicates the compatibility of the ligands. CONCLUSIONS 1. For the first time, a systematic study of homo- and heteroligand complexes of cobalt(II) and nickel(II) with monoamine carboxymethyl complexones (IDA, GEIDA, NTA, MGDA) and saturated dicarboxylic acids (oxalic, malonic, succinic) in aqueous solutions was carried out. 34 homoligand complexes in 14 binary and 65 heteroligand complexes in 24 ternary systems were identified. Copyright JSC Central Design Bureau BIBKOM & LLC Kniga-Service Agency 16 2. The influence of various factors on the nature of protolytic equilibria and the completeness of complex formation has been established. The accumulation fractions were calculated for all homo- and heteroligand complexes depending on the acidity of the medium and the concentration of the reacting components. The stoichiometry of the complexes at different pH values, as well as the regions of their existence at different ligand concentrations, were determined. 3. It has been established that in solutions of oxalates and malonates Co(II) and Ni(II) there are three types of complexes + and 2–, and in solutions of succinates only two monocomplexes of composition + and are found. To increase the proportion of dicarboxylate accumulation, a multiple increase in the content of dicarboxylic acids is required. In this case, not only the stoichiometry, but also the pH ranges of existence of these complexes can change. 4. It has been shown that the stoichiometry of complexes in the M(II) – HxComp systems depends on the acidity of the medium and the concentration of ligands. In acidic media, in all systems, complexes 2–x are first formed, which in weakly acidic solutions are converted into biscomplexonates 2(1–x) with increasing pH. For a 100% accumulation of complexes, a two to threefold excess of ligand is required, while the formation of complexes shifts to a more acidic region. To complete the formation of complexes – and – an excess of complexone is not required. In an alkaline environment, complexonates are hydrolyzed to form 1–x. 5. For the first time, complex formation equilibria in ternary systems M(II)–HxComp–H2Dik were studied and heteroligand complexes of composition 1–x, x–, 2x– and (1+x)– were discovered. It has been established that the accumulation fractions of these complexes and the sequence of their transformation depend on the acidity of the medium and the concentration of the dicarboxylic acid. Based on the values of coproportionation constants, the compatibility of ligands in the coordination sphere of metal cations was established. 6. Two mechanisms of heteroligand complex formation have been identified. The first of them is dicarboxylate-complexonate, in which the role of the primary structure-setting ligand is played by the dicarboxylic acid anion. This mechanism is implemented in all systems of the M(II)–HxComp–H2Ox type, as well as in some systems M(II)–HxComp–H2Dik, where HxComp are H2Ida and H2 Heida, and H2Dik are H2Mal and H2Suc. The second mechanism is complexonatodicarboxylate, where the structure-setting ligand is a complexone or metal complexonate. This mechanism is manifested in all systems M(II)–H3Comp–H2Dik, where H3Comp is H3Nta and H3Mgda, and H2Dik is H2Mal and Copyright JSC Central Design Bureau BIBKOM & LLC Kniga-Service Agency 17 H2Suc. Both mechanisms indicate the sequence of binding of the studied ligands into a heteroligand complex with increasing pH. 7. The stability constants of homo- and heteroligand complexes were calculated, the optimal ratios M(II) : H3Comp: H2Dik and the pH values at which the concentrations of complex particles reached their maximum were determined. It was found that the logβ values of homo- and heteroligand complexes increase in the series:< < , < < – < –, 2– ≈ 2– < 4– ≈ 4–, 2– < 2– < 3– < 3–, которые обусловлены строением, основностью и дентатностью хелатов, размерами хелатных циклов, а также величиной координационного числа металла и стерическими эффектами. Основные результаты диссертации опубликованы в ведущих журналах, рекомендованных ВАК: 1. 2. 3. 4. 5. Корнев В.И., Семенова М.Г., Меркулов Д.А. Однороднолигандные и смешанолигандные комплексы кобальта(II) и никеля(II) с нитрилотриуксусной кислотой и дикарбоновыми кислотами // Коорд. химия. – 2009. – Т. 35, № 7. – С. 527-534. Корнев В.И., Семенова М.Г. Физико-химические исследования равновесий в системах ион металла – органический лиганд. Часть 1. Взаимодействие кобальта(II) с 2-гидроксиэтилиминодиацетатом в водных растворах дикарбоновых кислот // Бутлеровские сообщения. – 2009. – Т.17, №5. – С.54-60. Семенова М.Г., Корнев В.И. Комплексонаты кобальта(II) и никеля(II) в водных растворах щавелевой кислоты // Химическая физика и мезоскопия. – 2010. – Т. 12, № 1. – С. 131-138. Корнев В.И., Семенова М.Г., Меркулов Д.А. Гетеролигандные комплексы кобальта(II) и никеля(II) с иминодиуксусной и дикарбоновыми кислотами в водном растворе // Коорд. химия. – 2010. – Т. 36, № 8. – С. 595-600. Семенова М.Г., Корнев В.И., Меркулов Д.А. Метилглициндиацетаты некоторых переходных металлов в водном растворе // Химическая физика и мезоскопия – 2010. – Т.12, № 3. – С.390-394. Copyright ОАО «ЦКБ «БИБКОМ» & ООО «Aгентство Kнига-Cервис» 18 в других изданиях: 6. 7. 8. 9. 10. 11. 12. 13. 14. Корнев В.И., Семенова М.Г. Гетеролигандные комплексы кобальта(II) с нитрилотриуксусной кислотой и дикарбоновыми кислотами // Вестник Удм. Университета. Физика. Химия – 2008. – № 2. – С. 65-72. Семенова М.Г., Корнев В.И, Меркулов Д.А. Исследование равновесий в водных растворах дикарбоксилатов кобальта(II) и никеля(II) // Всероссийская конференция «Химический анализ» – Тез. докл. – Москва-Клязьма, 2008 – С. 93-94. Корнев В.И., Семенова М.Г., Меркулов Д.А. Взаимодействие никеля(II) с нитрилотриуксусной кислотой в присутствии дикарбоновых кислот // Девятая Российская университетско-академическая научно-практическая конференция: Материалы конференции – Ижевск, 2008 – С. 103-105. Семенова М.Г., Корнев В.И. Смешанолигандное комплексообразование кобальта(II) с нитрилотриуксусной кислотой и дикарбоксилатами // Девятая Российская университетско-академическая научно-практическая конференция: Материалы конференции – Ижевск, 2008 – С. 107-109. Семенова М.Г., Корнев В.И. Гетеролигандные комплексы 2гидроксиэтилиминодиацетата кобальта(II) и дикарбоновых кислот // XXIV Международная Чугаевская конференция по координационной химии и Молодежная конференция-школа «Физико-химические методы в химии координационных соединений» – Санкт-Петербург, 2009. – С. 434-435. Корнев В.И., Семенова М.Г., Меркулов Д.А. Метилглициндиацетатные комплексы некоторых переходных металлов в водно-дикарбоксилатных растворах // Десятая Российская университетско-академическая научнопрактическая конференция: Материалы конференции – Ижевск, 2010 – С. 101-102. Корнев В.И., Семенова М.Г. Взаимодействие кобальта(II) и никеля(II) c комплексонами ряда карбоксиметиленаминов и малоновой кислотой в водном растворе // Вестник Удм. Университета. Физика. Химия. – 2010. – № 1. – С. 34-41. Корнев В.И., Семенова М.Г. Кислотно-основные и комплексообразующие свойства метилглициндиуксусной кислоты // Десятая Российская университетско-академическая научно-практическая конференция: Материалы конференции – Ижевск, 2010 – С. 104-105. Семенова М.Г., Корнев В.И. Метилглицинатные комплексы кобальта (II) и никеля(II) в водно-дикарбоксилатных растворах // Вестник Удм. Университета. Физика. Химия – 2010 – № 2. – С. 66-71.
-> Add materials to the site -> Metallurgy -> Dyatlova N.M. -> "Complexones and metal complexonates" ->
Complexons and metal complexonates - Dyatlova N.M.
Dyatlova N.M., Temkina V.Ya., Popov K.I. Complexons and metal complexonates - M.: Khimiya, 1988. - 544 p.Download(direct link) : kompleksoniikkomplecsatori1988.djvu Previous 1 .. 145 > .. >> Next
It has been established that complexons stabilize non-transition elements in the +3 oxidation state in relation to the processes of hydrolysis and polymerization that are very characteristic of them. As a result, for example, indium in the presence of complexons is able to interact with ligands such as ammonia, pyridine, thio-sulfate, sulfite ion; thallium(III)-with o-phenantroline, for which coordination with these elements is uncharacteristic.
Mixed-ligand complexes exhibit significant stability. The probability of their formation increases with increasing radius during the transition from aluminum to thallium and as the denticity of the complexone decreases. In the case of indium, as a rule, the number of monodentate ligands included in the coordination sphere does not exceed three; for example, very stable complexonates are known: 2-, 3~, 3-. Indium complexonates have been successfully used to produce indium-gold alloys from alkaline media.
In normal complexes with complexones - derivatives of dicarboxylic acids, in particular 1,3-diaminopropylene-Ni-disuccinic and 2-hydroxy-1,3-diaminopropylene-Ni-disuccinic, the same patterns are observed as for traditional ligands type EDTA, however, differences in the stability of complexonates of neighboring elements of the group are significantly lower than those of EDTA complexes. The absolute values of the stability constants were also lower. Thus, for aluminum and gallium the ratio Kod/Km for both dicarboxylic acids is approximately equal to 10.
Increased stability of gallium and indium complexonates was recorded in normal complexons N,N"-6hc(2-hydroxybenzyl)ethylenediamine-Ni-diacetic acid. For both elements, the value of /Cml turned out to be equal to ^lO40 (at 25°C and [x = 0 ,1). However, the difference in the values of the logarithms of the stability constants was only 0.09. For phosphorus-containing complexons, the differences in the stability of aluminum and indium complexonates also turned out to be insignificant.
Thallium(III) is a strong oxidizing agent, therefore complexes with complexones with strong restorative properties. At the same time, the introduction of complexones into a solution containing Tl111 stabilizes it with respect to the action of reducing agents. For example, it is well known that the rate of redox
The interaction of thallium (III) with hydrazine sulfate is great. The introduction of complexons such as HTA, EDTA into a solution of Th (SO*) significantly slows down the reduction process with hydrazine sulfate, and in the case of DTPA at pH = 0.7-2.0, no redox interaction was detected even at 98 °C . It is noted that, in general, the rate of the redox reaction depends on pH in a rather complex way.
Complexons of the aminocarbon series can also be oxidized by thallium (III). It has been established that, as a result of complexation, a ligand such as ethylenediaminedimalonic acid is oxidized, albeit very slowly, in the acidic pH region already at room temperature; ethylenediaminedisuccinic acid is oxidized at 30-40 °C. In the case of CGDTA, oxidation occurs at a noticeable rate at 98 0C.
Thallium(I) is a weak complexing agent; the Kml value for aminocarboxylic acids lies in the range IO4-IO6. It is noteworthy that mono-protonated complexonates with CGDTA and DTPA were discovered for it; protonation of the complex does not lead, as in the case of alkali metal cations, to the complete destruction of the complexonate. However, there is a decrease in the stability of the complex by several orders of magnitude.
It is noteworthy that thallium(I) complexonate with CGDTA, despite its relatively low stability, turned out to be unstable on the NMR time scale, which made it an accessible object for spectroscopic studies.
Of the complexonates of non-transition elements of the germanium subgroup, compounds of germanium(IV), tin(IV), tin(II) and lead(II) have been described.
Due to their strong tendency to hydrolysis, germanium(IV) and tin(IV) form stable mononuclear complexonates only with highly dentate ligands, for example EDTA, HEDTA, EDTP, DTPP. Aqua-hydroxy ions of these elements, like similar complexes THTaHa(IV), zirconium(IV) and hafnium(IV), are relatively easily polymerized to form polygermanium and polytin acids. Often this process of consolidation ends with the formation colloidal particles. The introduction of complexones into aqueous solutions allows one to significantly expand the boundaries of the existence of true solutions of germanium (IV) and tin (IV). For example, germanium(IV) forms a mononuclear complex with EDTA, which is stable in neutral and alkaline environments up to pH = 10. The formation of complexes stable in aqueous solutions with ligands of the aminophosphone series NTP, EDTP, DTPP is observed in a wide range - from pH = 2 to alkaline solutions. Increasing the metal:ligand ratio
361 (above 1) leads to the formation of practically water-insoluble polynuclear compounds in germanium - phosphorus-containing ligand systems.