Complexes Of Divalent Metal Ions Research Articles

Solution Equilibria and Thermodynamic Studies of Complexation of Divalent Transition Metal Ions with Some Triazoles and Biologically Important Aliphatic Dicarboxylic Acids in Aqueous Media

The formation of binary and ternary complexes of the divalent transition metal ions CuII, NiII, ZnII, and CoII with some triazoles [1,2,4-triazole (TRZ), 3-mercapto-1,2,4-triazole, and 3-amino-1,2,4-triazole], and the biologically important aliphatic dicarboxylic acids adipic, succinic, malic, malonic, maleic, tartaric, and oxalic acid, was investigated in aqueous solutions using the potentiometric technique at 25 °C and I = 0.10 mol·dm−3 NaNO3. The formation of 1:1 and 1:2 binary complexes and 1:1:1 ternary complexes was inferred from the corresponding titration curves. The formation of ternary complexes occurs in a stepwise manner with the carboxylic acids acting as primary ligands. The ionization constants (pKa) of the investigated ligands were redetermined and used for determining the stability constants of the binary and ternary complexes formed in solution. The order of stability of the ternary complexes was investigated in terms of the nature of the triazole, carboxylic acid and metal ion used. The ∆log10K values, percent relative stabilization, and log10X for the ternary complexes have been evaluated and discussed. The concentration distributions of the various species formed in solution were evaluated. The ionization constants of TRZ and malic acid and stability constants of their binary and ternary complexes with CuII, NiII, and CoII metal ions were studied at four different temperatures (15, 25, 35, and 45 °C) and the corresponding thermodynamic parameters have been evaluated and discussed. The complexation behavior of ternary complexes was ascertained using conductivity measurements. In addition, the formation of ternary complexes in solution has been confirmed by using UV–visible spectrophotometry.

Sterically Encumbered Amidinates and Guanidinates of Calcium and Strontium

AbstractAn attempt to prepare Tmp‐C(NDipp)2Li by treatment of lithium tetramethylpiperidide (Li‐Tmp) with N,N′‐bis(2,6‐diisopropylphenyl)carbodiimide (Dipp‐N=C=N‐Dipp) failed, and ether degradation occurred instead, allowing the isolation of a few crystals of O=CH–CH=C(NH‐Dipp)2 (1) after hydrolytic work‐up. We then investigated calcium and strontium compounds. Metalation of PrisoH [Priso = iPr2N–C(N‐Dipp)2] with [(thf)2Ca{N(SiMe3)2}2] in refluxing hexane for 18 h yielded [{(Me3Si)2N}(thf)Ca(Priso)] (2). At room temperature, very few crystals of [Ca(Priso)2]·hexane (3) precipitated after several months from a saturated hexane solution of 2. KN(SiMe3)2 was added to a THF solution of [(thf)4CaI2] and PrisoH and heated to 60 °C for several hours yielding [(thf)Ca(Priso)(μ‐I)]2 (4). Metalation of PrisoH with [(thf)2Sr{N(SiMe3)2}2] led to formation of [Sr(Priso)2] (5) regardless of the applied stoichiometry. The reaction of N,N′‐bis(2,6‐diisopropylphenyl)benzamidine with KN(SiMe3)2 and [(thf)4CaI2] in THF followed by recrystallization from 1,2‐dimethoxyethane (dme) solution yielded [(dme)Ca{(Dipp‐N)2C–Ph}2] (6). The molecular structures of these compounds are discussed and compared with those of other encumbered complexes of divalent metal ions.

Interaction of d10 metal ions with thioether ligands: a thermodynamic and theoretical study

Thermodynamic parameters of complex formation between d(10) metal ions, such as Zn(2+), Cd(2+), Hg(2+) and Ag(+), and the macrocyclic thioether 1,4,7-trithiacyclononane ([9]AneS3) or the monodentate diethylsulfide (Et(2)S), in acetonitrile (AN) at 298.15 K, were studied by a systematic methodology including potentiometry, calorimetry and polarography. [9]AneS3 is able to form complexes with all the target cations, Et(2)S only reacts with Hg(2+) and Ag(+). Mononuclear ML(j) (j = 1, 2) complexes are formed with all the metal ions investigated, where the affinity order is Hg(2+) > Ag(+) > Cd(2+) ≈ Zn(2+) when L = [9]AneS3 and Hg(2+) > Ag(+) when L = Et(2)S. Enthalpy and entropy values are generally negative, as a consequence of both metal ion interactions with neutral ligands, the reagents' loss of degrees of freedom and the release of solvating molecules. DFT calculations on the complexes formed with [9]AneS3 in vacuum and in AN are also carried out, to correlate experimental and theoretical thermodynamic values and to highlight the interplay between the direct metal-thioether interaction and the solvation effects. Trends obtained for the stability constants and enthalpies of the 1 : 1 and 1 : 2 complexes in solvent well reproduce the experimental ones for all the divalent metal ion complexes with [9]AneS3 and indicate the release of 3 AN molecules in the formation of each consecutive octahedral complex. In addition, calculated and experimental values for Ag(+) complex formation in solution suggest that in AgL(2) species [9]AneS3 ligands are not both tridentate.

Comparative study of binding strengths of heavy metals with humic acid

The complexation of humic acid with certain heavy metal ions (Co(II), Ni(II), Cu(II), Zn(II) and Pb(II)) was investigated. The stability constants of humate complexes were determined by method which is based on distribution of metal ions between solution and resin in the presence and the absence of ligand, known as Schubert?s ion exchange method. Experiments were performed at 25 ?C, at pH 4.0 and ionic strength of 0.01 mol dm-3. It was found that the 1:1 complexes were formed between metal ions and humic acid. Obtained results of the stability constants, log ?mn, of complexes formed between the metal ions and humic acid follow the order Co(II) < Ni(II) < Cu(II) > Zn(II) which is the same like in the Irving-Williams series for the binding strength of divalent metal ion complexes. Stability constant of complex between Pb(II) ions and humic acid is greater than stability constants of other investigated metal-humate complexes. The investigation of interaction between heavy metal ions and humics is important for the prediction of the distribution and control of the migration of heavy metals in natural environment.

Structural and Spectroscopic Trends in a Series of Half-Sandwich Scorpionate Complexes

Fifteen half-sandwich scorpionate complexes [(L)M(NCMe)(3)](BF(4))(n) (L = tris(3,5-dimethylpyrazol-1-yl)methane, Tpm(Me,Me), n = 2, 1(M), M = Mn, Fe, Co, Ni; L = tris(3-phenylpyrazol-1-yl)methane, Tpm(Ph), n = 2, 2(M), M = Mn, Fe, Co, Ni; L = hydrotris(3,5-dimethylpyrazol-1-yl)borate, [Tp(Me,Me)](-), n = 1, 3(M), M = Fe, Co, Ni; L = hydrotris(3-phenyl-5-methylpyrazol-1-yl)borate, [Tp(Ph,Me)](-), n = 1, 4(M), M = Mn, Fe, Co, Ni) were prepared by addition of the tripodal ligands to solvated [M(NCMe)(x)](2+) (M = Mn, x = 4; M = Fe, Co, Ni, x = 6) precursor complexes. The product complexes were characterized by (1)H NMR (except M = Mn), UV-vis-NIR, and FTIR spectroscopy. The structures of 2(Mn), 2(Ni), 3(Fe), 3(Co), and 4(Fe) were determined by X-ray crystallography. The data were consistent with complexes of high-spin divalent metal ions in idealized piano-stool geometries in all cases. Consequent lability of the acetonitrile ligands will enable use of these complexes as synthetic precursors and as catalysts. Comparison to previously reported structures of 1(Fe), 1(Co), 2(Fe), and 2(Co), the triflate salt analogues of 4(Co) and 4(Ni), as well as related sandwich complexes (e.g., [(Tp(Me,Me))(2)M]) and solvated metal dications [M(NCMe)(6)](2+) reveals numerous trends in M-N bond lengths. Primary among these are the Irving-Williams series, with significant structural effects also arising from ligand charge and sterics. Systematic trends in spectroscopic data were also observed which further elucidate these issues.

Complexation of divalent metal ions with diols in the presence of anion auxiliary ligands: zinc‐induced oxidation of ethylene glycol to glycolaldehyde by consecutive hydride ion and proton shifts

Ternary complexes of the type AH•••M(2+)•••L(-) (AH = diol, including diethylene and triethylene glycol, M = Ca, Mn, Fe, Co, Ni, Cu and Zn and auxiliary anion ligand L(-) = CH(3)COO(-), HCOO(-) and Cl(-)) have been generated in the gas phase by MALDI and ESI, and their dissociation characteristics have been obtained. Use of the auxiliary ligands enables the complexation of AH with the divalent metal ion without AH becoming deprotonated, although A(-)•••M(2+) is often also generated in the ion source or after MS/MS. For M = Ca, dissociation occurs to AH + M(2+)•••L(-) and/or to A(-)•••M(2+) + LH, the latter being produced from the H-shifted isomer A(-) •••M(2+)•••LH. For a given ligand L(-), the intensity ratio of these processes can be interpreted (barring reverse energy barriers) in terms of the quantity PA(A(-)) - Ca(aff) (A(-)), where PA is the proton affinity and Ca(aff) is the calcium ion affinity. Deuterium labeling shows that the complex ion HOCH(2)CH(2) OH•••Zn(2+)•••(-)OOCCH(3), in addition to losing acetic acid (60 Da), also eliminates glycolaldehyde (HOCH(2)CH=O, also 60 Da); it is proposed that these reactions commence with a hydride ion shift to produce the ion-dipole complex HOCH(2)CHOH(+)••• HZnOOCCH(3), which then undergoes proton transfer and dissociation to HOCH(2)CH=O + HZn(+)•••O = C(OH)CH(3). In this reaction, ethylene glycol is oxidized by consecutive hydride ion and proton shifts. A minor process leads to loss of the isomeric species HOCH=CHOH.

Speciation studies of ternary complexes of some essential divalent metal ions with L-histidine and L-glutamic acid in DMSO-water mixtures

Chemical speciation of ternary complexes of Ca(II), Mg(II) and Zn(II) ions with L-histidine as the primary ligand (L) and L-glutamic acid as the secondary ligand (X) has been studied pH metrically in the concentration range of 0.0-60.0% v/v DMSO-water mixtures maintaining an ionic strength of 0.16 mol L-1 using sodium chloride at 303.0 K. Titrations were carried out in different relative concentrations (M:L:X = 1.0:2.5:2.5, 1.0:2.5:5.0, 1.0:5.0:2.5) of metal (M) to L-histidine to L-glutamic acid with sodium hydroxide. Stability constants of ternary complexes were refined with MINIQUAD75. The best-fit chemical models were selected based on statistical parameters and residual analysis. The predominant species detected for Ca(II), Mg(II) and Zn(II) are ML2XH2, MLXH2 and MLX2. Extra stability of ternary complexes compared to their binary complexes was explained to be due to electrostatic interactions of the side chains of ligands, charge neutralisation, chelate effect, stacking interactions and hydrogen bonding. The species distribution with pH at different compositions of DMSO and the plausible equilibria for the formation of species are discussed.

Macrocycles incorporating isomeric arms: synthesis and crystal structures of ligands and their mono-, di- and polynuclear supramolecular complexes

An isomeric series of NS2-macrocycles containing a pyridine-arm at the ortho (o-L), meta (m-L) and para (p-L) positions were synthesized and structurally characterised by X-ray analysis. A comparative investigation of the coordination behaviour of these ligands with AgI, HgII, PbII and CuII is reported. The X-ray structures of seven complexes (1–7) have been determined, and a range of structural types and coordination modes including mono- to multinuclear and discrete to continuous ones, are shown to occur. Reactions of these ligand isomers with AgI salts (ClO4− and NO3−) afforded four complexes (1–4): the monomer (1 : 1, metal-to-ligand) complex with a trigonal bipyramid (TBP) geometry [Ag(o-L)ClO4] (1), the anion-free cyclic dimer (2 : 2) complex with two separated units, [Ag2(m-L)2]2(ClO4)4 (2), the cyclic dimer complex [Ag2(p-L)2](ClO4)2·CH3CN (3) and the unique poly(cyclic dimer) network complex {[Ag2(p-L)2(NO3)]NO3}n (4). Three divalent metal ion (mercury, lead and copper) complexes (5–7) of o-L were also isolated: the 1 : 1 monomer complexes with a square pyramid (SP) geometry [Hg(o-L)(NO3)2] (5) and [Cu(o-L)(H2O)ClO4]ClO4 (6) and the anion-linked dinuclear complex [Pb2(o-L)2(CH3OH)2(μ2-ClO4)2](ClO4)2 (7), adopting a monocapped trigonal prismatic geometry. In all cases, the pyridine arms with the different nitrogen positions have an important role in their three dimensional coordination behaviours via the strong Npy-M bonds. Also their coordination patterns depend markedly on the variation of the pyridyl nitrogen positions especially for m-L and p-L due to the preference of the network formation with discrete or continuous structures.

Conformational Analysis of 18-Azacrown-6 and Its Bonding with Late First Transition Series Divalent Metals: Insight from DFT Combined with NPA and QTAIM Analyses

Density functional theory calculations, together with quantum theory of atoms in molecules (QTAIM) analyses, have been performed to investigate 18-azacrown-6 complexes of the high-spin late first transition series divalent metal ions in the gas phase and, in some cases, in aqueous solution simulated by a polarizable continuum model. Six intramolecular H-H bonding interactions in the meso-complexes are found to arise from folding of the ligand upon its electrostatic interaction with the metal ions, which are largely absent in the lowest-energy C(2h) conformer of the free ligand. The ligand-to-metal charge transfer obtained from QTAIM analysis, among other things, is found to be an important factor that controls the stability of these complexes. The inter-relationship between the ligand preorganization energy, the zero-point corrected formation energy of the metal complexes, and the H-H bonding pair distances, as well as the dependence of the electron density and the total energy density at the H-H bond critical points on the H-H bonding pair distances, provides a physical basis for understanding and explaining the stabilizing nature of these closed-shell interactions, which are often viewed as steric clashes that lead to complex destabilization.

Polarographic Behavior of Manganese(II) in the Presence of Oxalate Ions in Perchlorate and Sulfate Solutions

The dc polarographic method has been applied to study coordination equilibria between Mn(II) and oxalate ions in perchlorate and sulfate solutions. The stoichiometries of complexes formed in solution and those reduced at a dropping mercury electrode were established. The stability constants of the Mn(II) oxalate and sulfate complexes, as well as their diffusion coefficients, were determined at a constant ionic strength 0.5 mol⋅L−1 and 25 °C. The stabilities of these Mn(II) complexes were compared with the corresponding complexes of other divalent metal ions. The polarographic method was able to identify complexes that have not been established by other methods and to determine their stability constants with high accuracy.

Synthesis, spectroscopic studies, and antibacterial activities of 14-membered tetraazamacrocyclic complexes of divalent transition metal ions

A new series of macrocyclic complexes, [M(C48H32N4)X2], where M = Co(II), Ni(II), Cu(II), and Zn(II); X = Cl−, NO3 −, CH3COO−, have been synthesized by condensation of 1,8-diaminonaphthalene and benzil, in the presence of divalent metal salts in methanolic medium. The complexes have been characterized by elemental analyses, conductance measurements, magnetic measurements, and electronic, NMR, IR, and MS spectral studies. The low value of molar conductance indicates the presence of non-electrolytes. A distorted octahedral geometry is proposed for the complexes. The metal complexes were also tested for their in vitro antibacterial activities against some bacterial strains and compared with the standard antibiotic Ciprofloxacin. Some tested complexes show good antibacterial activities against some bacterial strains.

Potentiometric Study on Complexation of Divalent Transition Metal Ions with Amino Acids and Adenosine 5′-Triphosphate

Potentiometric equilibrium measurements have been performed at 25 °C and in an I = 0.10 M KCl ionic medium for the interaction of nickel(II), copper(II), and zinc(II) with adenosine 5′-triphosphate (ATP) and dicarboxylic amino acids (aa): aspartic acid (Asp) and glutamic acid (Glu). The formation of 1:1 and 1:2 binary and 1:1:1 ternary complexes was inferred from the potentiometric titration curves. It was deduced that adenosine 5′-triphosphate acts as a primary ligand in the ternary complexes involving the dicarboxylic amino acids. The complexation model for systems of adenosine 5′-triphosphate (ATP) and the dicarboxylic amino acids with nickel(II), copper(II), and zinc(II) have been established by the “BEST” software from the potentiometric data. Values of Δ log K (log βMAB − (log βMA + log βMB)) showed that the ternary complexes are less stable than the binary ones, suggesting that no interaction occurred between the ligands in the ternary complexes. The order of the values of the stability constants of all the ternary complexes was M(II)ATP(Asp) > M(II)ATP(Glu), and the same sequence was found in the binary complexes of metal ions with the amino acids. With respect to the metal ions, the stability constants of binary and ternary complexes decrease in the following order: copper(II) > nickel(II) > zinc(II).

Macrocyclic complexes of divalent transition metal ions derived from succinyldihydrazide and diacetyl with their antibacterial studies

Condensation of succinyldihydrazide with diacetyl in the presence of divalent metal ions in the molar ratio of 1 : 1 : 1 resulted in the formation of [M(C8H12N4O2)X2], where M = Co(II), Ni(II), Cu(II), Zn(II), and X = Cl−, , CH3COO−. The complexes have been characterized with the aid of various physicochemical techniques, such as elemental analyses, conductance measurements, electronic, NMR, EPR, and IR spectral studies. On the basis of these studies, a distorted octahedral geometry in which two nitrogens and two carbonyl oxygens were coordinated have been proposed for all the complexes. The complexes were also tested for their in vitro antibacterial activities against some bacterial strains and compared with standard antibiotic Ciprofloxacin. Some of the complexes showed good antibacterial activities against selected bacterial strains.

Synthesis, Characterization, and Antimicrobial Activities of Macrocyclic Complexes of Divalent Transition Metal Ions

A novel series of complexes of the type [M(C 36 H 22 N 6 )X 2 ]; where M = Co(II), Ni(II), Cu(II) and Zn(II); X = Cl−, NO3 −, CH3COO−has been synthesized by template condensation of 1,8-diaminonaphthalene and Isatin in the presence of divalent metal salts in methanolic medium. The complexes have been characterized by elemental analyses, conductance and magnetic measurements, UV/Vis, NMR, IR and MS spectroscopy. On the basis of these spectral data, a distorted octahedral geometry may be proposed for all of these complexes. All synthesized macrocyclic complexes were tested for in vitro antimicrobial activities against some pathogenic bacterial and fungal strains.

Synthesis and spectral study of biologically active macrocyclic complexes of divalent transition metal ions

The condensation reaction of succinyldihydrazide with glyoxal in the presence of divalent metal ions (1: 1: 1) results in the formation of the complexes of type [M(C6H8N4O2)X2], where M = Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and X = Cl−, NO 3 − , CH3COO−. The complexes have been characterized with the aid of elemental analyses, conductance measurements and electronic, NMR, infrared spectral studies. On the basis of these studies, a six-coordinated distorted octahedral geometry in which two nitrogen and two carbonyl oxygen atoms are suitably placed for coordination toward metal ion, has been proposed for all the complexes. The complexes were tested for their in vitro antibacterial activity. Some of the complexes showed remarkable antibacterial activities against some selected bacterial strains.

Coordinated cations in dipicolinato complexes of divalent metal ions

Abstract Several salts of alkali, alkaline earth metal and organic ammonium cations of a complex anion [ML 2 ] 2− {Where L = dipicolinato dianion, M = copper(II), nickel(II) and zinc(II)} are prepared. The coordination effect of [ML 2 ] 2− with the cations such as sodium, potassium, calcium, magnesium, and organic cations namely diammonium cation of 1,5-pentanediamine, diammonium cation of 1,8-octyldiamine, mono ammonium cation of 4-aminobenzylamine are studied by determining their X-ray crystal structures. Depending on the nature of cations, four different types of structures are obtained. When calcium is the cation a polymeric structure with calcium ions bridging the [ML 2 ] 2− is observed. The salts having sodium and potassium cations form polymeric chain like structures by oxo and aqua bridges. In the case of magnesium, the hydrated form of magnesium cations coordinates to [ML 2 ] 2− . The organic ammonium salts of [ML 2 ] 2− have the structural features of conventional ionic complexes. These salts easily exchange cations. The organic ammonium salts of [ML 2 ] 2− decomposes to give the corresponding metal oxides at relatively low temperature range 300–450 °C.

Potentiometric and conductometric studies of malonyl bis(salicyloylhydrazone) and divalent metal complexes

A series of complexes of divalent transition metal ions with malonyl bis(salicyloylhydrazone) (H4MSH) have been prepared and characterized with the help of conductometric, potentiometric methods. The proton–ligand and metal–ligand stability constants were obtained pH-metrically. The electrical conductivity of solid complexes was measured at 289K. The low molar conductance values observed for these complexes indicate that, they are non-electrolytes. They are soluble to a limited extent in DMF and DMSO. The elemental analyses of the complexes indicate that the complexes have 1:1 and 2:1 (M:L) stoichiometry with the existence of water, chloride, acetone molecules inside the coordination sphere as evidence from the IR spectral studies. Further, the complexes have been formulated by comparing C, H, N & metal analysis data, and UV–visible spectra of the complexes have been discussed. The protonation constants of the ligand and the stability constants of their metal complexes will be evaluated potentiometrically. The stoichiometric ratios of the complexes formed in solution will be evaluated applying the molar ratio (spectrophotometric) method and confirmed conductometrically.

Synthesis and Characterization of a New N"‐[(1Z,2E)‐2‐ (Hydroxyimino)‐1‐phenylpropylidene]‐N"′‐[(1E)‐phenylmethylene]thiocarbonohydrazide and its Complexes with Co(II), Ni(II) and Cu(II)

Synthesis and characterization of a new N"‐[(1Z,2E)‐2‐ (Hydroxyimino)‐1‐phenylpropylidene]‐N"′‐[(1E)‐phenylmethylene]thiocarbonohydrazide and its metal complexes with Co(II), Ni(II) and Cu(II) metal ions. The ligand synthesis and characterization is reported for first time. The complexes of divalent metal ions were synthesized in 1:2 molar proportion using ethanol as solvent. The ligands as well as its metal complexes were characterized using various physicochemical techniques such as elemental analysis, spectral and magnetic measurements and electrical conductivity measurements in case of the metal complexes only. The data for the metal complexes reveals that they may be represented by ML2. The metal complexes show interesting features of coordination structure.

New 14-membered octaazamacrocyclic complexes of divalent transition metal ions with their antimicrobial and spectral studies

A novel series of macrocyclic complexes of the type [M(C(18)H(14)N(10)S(2))X(2)]; where M=Co(II), Ni(II), Cu(II), Zn(II) and Cd(II); X=Cl(-), NO(3)(-), CH(3)COO(-) has been synthesized by [2+2] condensation of thiocarbohydrazide and isatin in the presence of divalent metal salts in methanolic medium. The complexes have been characterized with the help of elemental analyses, conductance measurements, magnetic measurements, electronic, NMR and infrared spectral studies. The low value of molar conductance indicates them to be non-electrolytes. On the basis of various studies a distorted octahedral geometry may be proposed for all of these complexes. These metal complexes were also tested for their in vitro antimicrobial activities against some Gram-positive bacteria viz. Staphylococcus aureus, Bacillus subtilis, and some Gram-negative bacteria Escherichia coli, Pseudomonas aeruginosa and some fungal strains Aspergillus niger, Aspergillus flavus (molds), Candida albicans, Saccharomyces cerevisiae (yeasts). The results obtained were compared with standard antibiotic: Ciprofloxacin and the standard antifungal drug: Amphotericin-B.

Potentiometric Investigation on Complexation of Divalent Transition Metal Ions with Some Zwitterionic Buffers and Triazoles

The interaction between the zwitterionic buffers N-(2-acetamido)iminodiacetic acid (ADA), N-[tris(hydroxymethyl)methyl]glycine (tricine), and N,N-bis(2-hydroxyethyl)glycine (bicine) and 1,2,4-triazole (TRZ), 3-mercapto-1,2,4-triazole (TRZSH), and 3-amino-1,2,4-triazole (TRZAM) with the divalent transition metal ions, Cu2+, Ni2+, Zn2+, and Co2+, was investigated in aqueous media at 25 °C and ionic strength I = 0.1 mol·dm−3 NaNO3 using the potentiometric technique. The acid−base properties of the ligands were investigated and discussed. The acidity constants of the ligands were determined and used for determining the stability constants of the different complexes formed in solution. The formation of the different 1:1 and 1:2 binary complexes and 1:1:1 ternary complexes is inferred from the corresponding titration curves. The ternary complex formation was found to occur in a stepwise manner. The order of stability of the complexes formed in solution was investigated in terms of the nature of the zwitterionic buffer, triazole, and metal ion used. The values of Δlog K, percentage of relative stabilization (% R.S.), and log X for the mixed-ligand complexes studied have been evaluated and discussed. The concentration distribution of the various species formed in solution was evaluated. The ionization processes of ADA and TRZAM and their interaction with Cu2+, Ni2+, and Co2+ were studied at different temperatures [(15, 25, 35, and 45) °C], and the corresponding thermodynamic parameters have been evaluated and discussed. In addition, the dissociation constants of ADA and TRZAM and stability constants of their 1:1 binary and 1:1:1 ternary complexes with Ni2+ in various water + dioxane mixtures at 25 °C were determined and discussed.