- Solubility, complex formation, and redox reactions in the Tl 2O3-HCN/CN--H2O system. Crystal structures of the cyano compounds Tl(CN)3·H2O, Na[Tl(CN)4]·3H2O, K[Tl(CN)4], and TlITlIII(CN)4 and of TlI 2C2O
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Thallium(III) oxide can be dissolved in water in the presence of strongly complexing cyanide ions. TlIII is leached from its oxide both by aqueous solutions of hydrogen cyanide and by alkali-metal cyanides. The dominating cyano complex of thallium(III) obtained by dissolution of Tl 2O3 in HCN is [Tl(CN)3(Bq)] as shown by 205Tl NMR. The Tl(CN)3 species has been selectively extracted into diethyl ether from aqueous solution with the ratio CN -/TlIII = = 3. When aqueous solutions of the MCN (M = Na+, K+) salts are used to dissolve thallium(III) oxide, the equilibrium in liquid phase is fully shifted to the [Tl(CN) 4]- complex. The Tl(CN)3 and Tl(CN) 4- species have for the first time been synthesized in the solid state as Tl(CN)3·H2O (1), M[Tl(CN) 4] (M = Tl (2) and K (3)), and Na[Tl(CN)4]·3H 2O (4) salts, and their structures have been determined by single-crystal X-ray diffraction. In the crystal structure of 1, the thallium(III) ion has a trigonal bipyramidal coordination with three cyanide ions in the equatorial plane, while an oxygen atom of the water molecule and a nitrogen atom from a cyanide ligand, attached to a neighboring thallium complex, form a linear O-Tl-N fragment. In the three compounds of the tetracyano-thallium(III) complex, 2-4, the [Tl(CN)4]- unit has a distorted tetrahedral geometry. Along with the acidic leaching (enhanced by TlIII-CN- complex formation), an effective reductive dissolution of the thallium(III) oxide can also take place in the Tl 2O3-HCN-H2O system yielding thallium(I), while hydrogen cyanide is oxidized to cyanogen. The latter is hydrolyzed in aqueous solution giving rise to a number of products including (CONH2) 2, NCO-, and NH4+ detected by 14N NMR. The crystalline compounds, TlI[Tl III(CN)4], TlI2C2O 4, and (CONH2)2, have been obtained as products of the redox reactions in the system.
- Nagy, Peter,Fischer, Andreas,Glaser, Julius,Ilyukhin, Andrey,Maliarik, Mikhail,Toth, Imre
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- Oxidative conversion of benzoic and o-chlorobenzoic acid hydrazides to their corresponding acids by thallium(III): A mechanistic study
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The reactions between thallium(III) and benzoic acid and o-chlorobenzoic acid hydrazides have been studied in a mixture of perchloric and hydrochloric acid medium. The reaction involves formation of complex between the reactants, which decompose in the subsequent step to give products. The reaction proceeds by direct two electron transfer without intervention of free radicals. Increase in [H+] and [Cl-] decreases the rate of the reaction. The increase in the ionic strength does not affect the rate of the reaction while decrease in the relative permitivity increases the same. The effect of temperature on the reaction has been studied between 25 to 45°C and the activation parameters were determined for the slow step of the reaction.
- Tardale,Phadkule,Patil,Gokavi
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- Kinetics and mechanism of electron transfer reactions in acetate buffers: Ruthenium (III) chloride catalysed oxidation of nitrite by thallium (III) acetate
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The oxidation of nitrite by thallium (III) in acetate buffers corresponds to the stoichiometry represented by Eq. The kinetic rate law (ii) accounts for the first order in each reactant and the retarding effect of acetate ions. [T1(III)], [HNO2] and [RuIII] are the gross analytical concentrations of the reactants and catalyst respectively. A plausible reaction mechanism has been suggested.
- Vijay,Sharma,Bhasin,Khandelwal,Sharma
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p. 708 - 713
(2007/10/03)
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- Kinetics of Electron Transfer Reaction of Thallic(III) Perchlorate with Glycerol
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The kinetics of electron transfer reaction of thallium(III) perchlorate with glycerol has been studied under the pseudo-first order conditions. Kinetic and spectrophotometric evidences suggest the formation of an intermediate complex between thallium(III) and glycerol in the pre-equilibrium step. A free radical mechanism has been suggested and rate law has been derived to explain the kinetic and other results.
- Arzare, Sapana,Dave-Gautam, Mangala,Fadnis, Anand G.
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p. 423 - 424
(2007/10/03)
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- Bis(nitrilotriacetato) Thallium(III) Complexes
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Thallium(III) oxide is completely dissolved in an aqueous suspension of nitrilotriacetic acid or in a solution of its disodium salt at the molar ratio Tl : Nta = 1 : 2. The bis(nitrilotriacetato) complex is the only thallium(III) complex identified in the resulting solution by 13C and 205Tl NMR. In the heterogeneous Tl2O3-Nta-H2O system, the Tl3+-NIa complex formation is accompanied by a redox reaction, which results in the formation of univalent thallium and a partial decarboxylation of the complexone. Introducing guanidinium or Tl+ cations into the solution affords crystals of {C(NH2)3}3[Tl(Nta)2] · 2H2O (I) and Tl3[Tl(Nta)2] (II), respectively. Compound I is triclinic, space group P1, a = 9.510(2) A?, b = 9.769(2) A?, c = 15.409(3) A?, α= 76.20(2)°, β= 89.81(2)°, γ= 88.96(2)°, Z = 2. Compound II is trigonal, space group R3, a = 7.989(3) A?, c = 25.960(9) A?, Z = 3. The coordination number of thallium(III) in either compound is eight. The thallium coordination polyhedra are a tetragonal antiprism (I) and a cube (II). Crystallochemical features of nitrilotriacetato complexes of metals with a coordination number of 7 or 8 are considered.
- Malyarik,Ilyukhin
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p. 865 - 874
(2008/10/08)
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- A New Photochemical Redox Method for the Estimation of Thallium(III) in the Presence of High Chloride Ion Concentrations catalysed by Iron(III)
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A photochemical titrimetric method is described for the determination of thallium(III) with oxalate in 0.5 M perchloric acid and in the presence of high chloride (6.0 mmol) and 0.001-0.002 mmol of iron(III) as catalyst.Thallium(III) is reduced to thallium(I) photochemically with oxalic acid in perchloric acid medium in the presence of excess of chloride using iron(III) as catalyst.The reduced thallium(I) is determined bromatometrically in 1.5-2.0 M HCl in the presence of methyl orange as indicator.The catalytic activity of iron(III) is atributed to its capacity to photochemically oxidise oxalate and the subsequent reaction between thallium(III) and iron(II) in chloride medium.A detailed mechanism is proposed for the catalytic reaction.
- Rao, M. S. Prasada,Kumari, V. V. L.,Rao, T. Siva,Rao, A. Rama Mohan
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p. 185 - 188
(2007/10/03)
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- Kinetics and mechanism of electron-transfer reactions of aquothallium(III) and coordinated thallium(III), oxidation of malonic acid with thallium(III) in perchlorate medium
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The reaction between thallium(III) and malonic acid (H2ma) studied in acid perchlorate medium corresponds to the stoichiometry as represented by equation 3Tl(III) + CH2(COOH)2 -> 3Tl(I) + HCOOH + CO2 + 6H+ Thallium(III) forms an intermediate complex and the reduction of thallium(III) occurs via an internal redox reaction of the complex.A suitable mechanism has been suggested and the energy and entropy of activation of the rate-determining step have been calculated.
- Rao, Indu,Mishra, S.K.,Sharma, P.D.
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p. 773 - 776
(2007/10/02)
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- Solvent Dependence of Kinetics and Equilibria of Thallium(I) Cryptates in relation to the Free Energies of Solvation of Thallium(I)
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Stability constant and dissociation rate constants of thallium(I) cryptates have been measured in several solvents at 25 deg C.The Tl+ cryptates are more stable and less sensitive to ligand cavity size than the corresponding complexes of the al
- Cox, Brian G.,Stroka, Jadwiga,Schneider, Irmgard,Schneider, Hermann
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p. 187 - 198
(2007/10/02)
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- Reduction Potentials of CO2- and the Alcohol Radicals
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Equilibrium constants were measured at 25 deg C for the reactions CO2.- + Tl+ CO2 + Tl0 (K = 0.2), CH2O.- + Tl+ CH2O + Tl0 (K = 0.005), CH3CHO.- + Tl+ CH3C
- Schwarz, H. A.,Dodson, R. W.
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p. 409 - 414
(2007/10/02)
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- Redox Chemistry of Hyponitrous Acid: Part I-Stoichiometry, Kinetics and Mechanism of Its Oxidation by Ethylenediaminetetraacetatothallium(III) in Aqueous Perchloric Acid Medium
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One mol of hyponitrous acid (H2N2O2) reacts with one mole of thallium(III) in acidic perchlorate solution initially yielding one mol of HNO3 and 1/2 mol of N2O gas.The likely subsequent steps are the oxidation of HNO2 by Tl(III), and the reaction between
- Goyal, Muni R.,Mittal, Rama K.,Gupta, Y. K.
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p. 487 - 493
(2007/10/02)
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