Equilibrium Studies of Alkyltin(IV) Complexes with D-Glucosamine

The acid-base and complex-formation equilibria involving glucosamine and its complexes with alkyltin(IV) chlorides have been studied by potentiometric technique. The results prove to a formation of 1 : 1 complex with trialkyltin(IV) and both 1 : 1 and 1 : 2 complexes with dialkyltin(IV) species. The stability constants in water were determined, the effects of temperature (from 15 to 35 °C) and ethanol (up to 88 vol.%) was studied and the speciation of the complexes was resolved.

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Comparative Studies on the Complex-Formation Equilibria of Mercury(II) with Acetylcysteine and Captopril

Zeitschrift für Physikalische Chemie ◽

10.1524/zpch.2000.214.1.045 ◽

2000 ◽

Vol 214 (1) ◽

Cited By ~ 2

Author(s):

H. Köszegi-Szalai ◽

T.L. Paál ◽

L. Barcza

Keyword(s):

Complex Formation ◽

Binding Sites ◽

Extraction Methods ◽

Liquid Extraction ◽

Complex Formation Equilibria ◽

Protonation Equilibria ◽

Liquid Liquid Extraction ◽

Formation Equilibria ◽

The Stability ◽

Extreme Stability

The complex-formation equilibria of mercury(II) with acetylcysteine and captopril have been studied by pH-metric and liquid-liquid extraction methods applying dithizone as a competitive ligand during the latter measurements. The stability constants of three differently protonated Hg(II)/ligand 1:2 complexes of extreme stability have been determined by the combination of extraction and pH-metric data.The formation of the less stabil Hg(II)-ligand 1:3 complexes with the coordination of three sulfhydrilate groups has been followed and the values of βThe differences in the Hg(II) complex formation and protonation equilibria between the two ligands and the possible binding sites in the complexes have been discussed.

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Complex Formation Equilibria between Ag(I) and Thioureas in Propan-2-ol

ISRN Inorganic Chemistry ◽

10.1155/2013/189394 ◽

2013 ◽

Vol 2013 ◽

pp. 1-5 ◽

Cited By ~ 3

Author(s):

Domenico De Marco

Keyword(s):

Complex Formation ◽

Background Electrolyte ◽

Complex Formation Equilibria ◽

Entropy Changes ◽

Enthalpy And Entropy Changes ◽

Formation Equilibria ◽

Enthalpy And Entropy ◽

The Stability ◽

Tetramethyl Thiourea ◽

Stepwise Formation

The complex formation equilibria between Ag(I) and thiourea (Tu), N methyl-Thiourea (MeTu), N,N′-dimethyl-Thiourea (Me2Tu), N,N,N′,N′ Tetramethyl-Thiourea (Me4Tu), N-ethyl-Thiourea (EtTu), N,N′ diethyl-Thiourea (Et2Tu), and N,N′-Ethylen-Thiourea (EnTu) in propan-2-ol as solvent medium have been investigated by potentiometry within the temperature range 10°C–40°C and self-determined ionic medium by (AgNO3) concentration range 6.36·10-6–3.83·10-5 m·dm−3 (no background electrolyte added). The experimental results can be interpreted with the stepwise formation of tris-coordinated complexes AgLn (n=1–3; hereafter charge is omitted). The stability constants log βn and the standard thermodynamic changes in enthalpy (ΔHn°) and entropy (ΔSn°) for overall complex formation reactions AgI+nL=AgLn (n=1–3) have been evaluated. The reactions are exothermic in nature and entropy disfavored for all the investigated ligands. The standard enthalpy and entropy changes for the stepwise reactions AgLn-1+L=AgLn have been evaluated by difference ΔΔHn°=ΔHn°-ΔHn-1° and ΔΔSn°=ΔSn°-ΔSn-1°. The stepwise enthalpy are mutually linearly related to the corresponding entropy changes with isoequilibrium temperatures Tiso=285, 305, and 363 K for n=1, 2, or 3 respectively.

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Coordination properties of N,O-carboxymethyl chitosan (NOCC). Synthesis and equilibrium studies of some metal ion complexes. Ternary complexes involving Cu(II) with (NOCC) and some biorelevant ligand

Open Chemistry ◽

10.2478/s11532-011-0116-5 ◽

2012 ◽

Vol 10 (1) ◽

pp. 59-70 ◽

Cited By ~ 15

Author(s):

Azza Shoukry ◽

Wafaa Hosny

Keyword(s):

Metal Ions ◽

Stability Constants ◽

Metal Ion ◽

Ternary Complexes ◽

Central Metal ◽

Magnetic Studies ◽

Complex Formation Equilibria ◽

Equilibrium Studies ◽

The Stability ◽

Solid Complexes

AbstractIn the present study, the acid-base equilibria of N,O-carboxymethy chitosan abbreviated as (NOCC), is investigated. The complex formation equilibria with the metal ions Cu(II), Ni(II), Co(II), Mn(II), and Zn(II) are investigated potentiometrically. The stability constant values of the binary and ternary complexes formed in solution were determined and the binding centers of the ligands were assigned. The relationships between the properties of the studied central metal ions as ionic radius, electronegativity, atomic number, and ionization potential, and the stability constants of the formed complexes were investigated in an effort to give information about the nature of chemical bonding in complexes and make possible the calculation of unknown stability constants. Cu(II), Ni(II), and U(VI) complexes with NOCC are isolated as solid complexes and characterized by conventional chemical and physical methods. The structures of the isolated solid complexes are proposed on the basis of the spectral and magnetic studies. The ternary copper(II) complexes involving NOCC and various biologically relevant ligands containing different functional groups, as amino acids and DNA constituents are investigated. The stability constants of the complexes are determined and the concentration distribution diagrams of the complexes are evaluated.

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Stability constants and complex formation equilibria between iron, calcium, and zinc metal ions with vitamin B9 and glycine

Complex Metals ◽

10.1080/2164232x.2014.941115 ◽

2014 ◽

Vol 1 (1) ◽

pp. 139-148 ◽

Cited By ~ 13

Author(s):

Ahmed E. Fazary ◽

Ahmed M. Ramadan

Keyword(s):

Complex Formation ◽

Metal Ions ◽

Stability Constants ◽

Complex Formation Equilibria ◽

Zinc Metal ◽

Vitamin B9 ◽

Formation Equilibria

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Complex Formation of Nickel(II) and Copper(II) with Barbituric Acid

ISRN Analytical Chemistry ◽

10.1155/2014/243175 ◽

2014 ◽

Vol 2014 ◽

pp. 1-5 ◽

Cited By ~ 4

Author(s):

Naciye Türkel ◽

M. Suat Aksoy

Keyword(s):

Complex Formation ◽

Stability Constants ◽

Binary Systems ◽

Barbituric Acid ◽

Dissociation Constants ◽

Individual Species ◽

Equilibrium Studies ◽

Ph Titration ◽

Titration Data ◽

The Stability

Equilibrium studies have been carried out on complex formation of M2+ ions (M = Ni and Cu) with L = barbituric acid (BA) in aqueous solution at 25.0±0.1°C and with an ionic strength of I=0.10 M (KNO3) in aqueous medium. The basicity of the ligand was also assessed by the determination of the dissociation constants of the ligand. The experimental pH titration data were analyzed with the help of the BEST computer program in order to evaluate the stability constants of the various species formed. The stability constants of the binary systems decrease in the order of Cu(II) > Ni(II). Distribution diagrams for the species were drawn showing the concentrations of individual species as a function of pH by the SPE software program.

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