Electron Transfer Studies of TIN(IV)/TIN(II) in Acid Media

Abstract

Cyclic voltammaetry of mixed tin(II)/tin(IV) solutions was investigated in 6M HCl on gold and mercury electrodes. It was found that the reduction of tin(II) to tin(iv) proceeded irreversibly while tin(II) to tin(IV) was reversible. Two forms of tin(IV) are postulated. The peak potential for the reduction of tin(IV) was a function of both tin(II) and tin(IV) while that for the oxidation of tin(II) was a function only of tin(II) concentration Potentials for all oxidations and reductions were a function of potential scan rate.     

Carbonyl allylations by allylic chlorides utilizing a reduction of tin(IV) iodide to triiodostannate(II) species with iodide sources

Carbonyl allylations by allylic chlorides either with tin(IV) iodide and tetrabutylammonium iodide (TBAI) in dichloromethane or with tin(IV) iodide and sodium iodide in 1,3-dimethylimidazolidin-2-one at room temperature produced the corresponding homoallylic alcohols. The carbonyl allylations probably proceeded via the reduction of tin(IV) iodide to triiodostannate(II) species with iodide sources such as TBAI and NaI, which led to the construction of a tin(IV)-catalytic cycle based on regeneration of tin(IV) iodide via the transmetalation of homoallyloxytriiodotin to homoallyloxytrimethylsilane with iodotrimethylsilane.     

Effect of citric acid and hydrochloric acid on the polarographic behaviour of tin: Application to the determination of tin(II) in presence of tin(IV) in the activating solutions of the electroless plating of polymers

A new method for the determination of tin(II) in presence of tin(IV) is described. The method is based on differential pulse polarography on the hanging mercury drop electrode (HMDE). The effect of citric acid and hydrochloric acid concentrations on the polarographic peaks of tin(II) and tin(IV) has been studied. In 1 M HCl, the total quantity of tin can be determined, as under these conditions, in the absence of complexing agents, eventual variations in the oxidation states, in any concentration ratio, do not affect the peak height and the peak potential. In 0.2 M HCl and 0.2 M citric acid, tin(II) can be determined selectively in presence of tin(IV), as under these conditions, tin(IV) does not present polarographic response, while a well-defined peak is observed for tin(II). The method is applied to determine tin(II) and total tin in the activating solutions of the electroless plating of polymers.     

Synthesis of both epimeric triacid ananlogs of kainic acid

A practical and cheap method for synthesis of C-4 carboxylic acid substituted kainic acid analogue 5 and its epimer 6 from trans-4-hydroxyproline is described. Using this method, more interesting intermediates and analogues could be obtained easily.     

The complexometry of tin(IV)

Tin(IV) very readily hydrolyses in solution, and forms hydrous tin oxide SnO(2)2.nH(2)O even in rather strongly acidic solution. In spite of a lack of reliable data on the hydrolysis of tin(IV) a consistent picture of the behaviour of tin(IV) in solution has been constructed. Some values for the formation of hydroxide and chloride complexes were deduced from electrochemical data. In agreement with more or less qualitative remarks by other investigators a value of log k(so) = -3 has been found for the solubility constant. For the stability constant of tin(IV)-EDTA, log K(SnY) = 34.5 was found experimentally. A survey is given of the pitfalls which exist in handling tin solutions. A back-titration procedure is presented that provides for the complexometric determination of tin(IV) at concentrations down to 3 ppm, with an error of 1% or better. Thorium is used as back-titrant with Semi-Xylenol Orange as indicator. The method has successfully been applied to the analysis of organotin compounds.     

A Comparative Study of the Synthesis and Ion Exchange Properties of Iodophosphates of Tin(IV), Zirconium(IV) and Iron(III): Separations of Metal Ions on Tin(IV)-iodophosphate Columns

Abstract

Iodates and iodophosphates of tin(IV), zirconium(IV) and iron(III) have been synthesized under varying conditions and studied their ion exchange behaviour. Among the various ion exchangers synthesized, tin(IV)-iodophosphate is chosen for detailed study owing to its highest ion exchange capacity and highest chemical stability. The most stable sample is prepared by mixing 0.1M stannic chloride, 0.1M potassium iodate and 0.1M potassium dihydrogen orthophosphate solutions in the volume ratio 1:1:2 respectively at pH 0–1. It is a monofunctional weak cation exchanger. Its ion exchange capacity for K⁺ is 1.6 meq/dry g. The thermal and chemical stabilities of this material have been determined and compared with Zr(IV)-phosphoiodate. Effect of heating on the properties of tin(IV)-iodophosphate has been determined. To explore the separation potential of tin(IV)-iodophosphate Kd values of different metal ions have been determined in organic solvents. A number of important separations of metal ions of industrial utility have been successfully achieved on the columns of tin(IV)-iodophosphate.     

Radical polymerization of styrene in the presence of Tin(IV) catecholate complexes

The synthesis of PS in the presence of diethyl(3,6-di-tert-butylcatecholato)tin(IV) tetrahydrofuranate and diphenyl(3,6-di-tert-butylcatecholato)tin(IV) tetrahydrofuranate has been studied. It has been found that such tin catecholates can act as chain length regulators in the polymerization of styrene and ensure a linear increase in molecular mass with conversion. Using the macroinitiators obtained in the presence of diphenyl(3,6-di-tert-butylcatecholato)tin(IV) tetrahydrofuranate, the postpolymerization of styrene has been carried out.     

Organic-solvent-free systems with phase separation as efficient and safe systems for extraction of metal ions

The possibilities of using organic-solvent-free extraction systems with phase separation, based on antipyrine derivatives, are examined. Ionic associates with tin(II) and tin(IV) anionic complexes and mixed chelates of indium with antipyrine and sulfosalicylic acid are extracted into the organic phase. The suggested systems show promise for the recovery and determination of macro- and microamounts of indium, tin(II), and tin(IV) ions.     

Synthesis of di-μ-OXO-tetra-（α-pentyloxy） tin（Ⅳ） phthalocyanine

Axially substituted tin phthalocyanines, namely dichloride-tetra-（α-pentyloxy） tin （Ⅳ） phthalocyanine 2, dihydroxy-tetra-（α-pentyloxy） tin （Ⅳ） phthalocyanine 3 and its dimmer di-μ-oxo-tetra-（α-pentyloxy） tin（Ⅳ） phthalocyanine 4 were synthesized. The catalytic effect of H2O-free CaCl2 in quinoline was used for condensation of dihydroxy tin phthalocyanine 3 to the cofacially array dimmer 4. Their structures were characterized by UV-vis, IR, elemental analysis, MS, as well as ^1HNMR spectroscopy.     

Ion-chromatographic determination of chloride and fluoride in electrolyte from the halogen tin-plating process

A simple and rapid procedure is proposed for the determination of chloride and free fluoride in tin electroplating fluid. Suppressor-column ion-chromatography is used after oxidation of hexafluorostannate(II) to hexafluorostannate(IV) with hydrogen peroxide. Concurrent determination of tin(II) and total tin then allows calculation of the concentrations of fluoride, hexafluorostannate(II) and hexafluorostannate(IV).     

Citrate complexes of tin(IV) studied by liquid-liquid extraction with 5,7-dichloro-8-quinolinol

The tin(IV)/5,7-dichloro-8-quinolinol/chloroform extraction system is used to determine the composition and the stability constants of the aqueous complexes of tin(IV) with citric acid, in the pH range 2.0–3.5. The tin(IV):citric acid ratios found are 1:1 and 1:2, depending on the concentration of the acid. The conditional stability constants are (5.5 ± 0.4) × 10³ and (1.3 ± 0.3) × 10³ for the 1:1 and 1:2 complexes, respectively. This extraction system is convenient in studies of aqueous tin(IV) complexes that cannot be extracted into chloroform.     

Solvent extraction separation of tin (IV) with 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (PC-88A)

Solvent extraction of tin(IV) from hydrochloric acid media was carried out with 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (PC-88A) in toluene. Tin(IV) was quantitatively extracted with 2.5x10(-2) M PC-88A in toluene from 0.1-0.3 M HCl when equilibrated for 5 min. Tin(IV) from the organic phase was stripped with 4 M HCl and determined spectrophotometrically by both the morin and pyrocatechol violet method. The nature of the extracted species was determined from the log-log plots. Various other diluents such as xylene, hexane and cyclohexane also gave quantitative extraction of tin. The metal loading capacity of the reagent was found to be 0-15 ppm of tin(IV). The extraction of tin(IV) was carried out in the presence of various ions to ascertain the tolerance limit of individual ions. Tin(IV) was successfully separated from commonly associated metal ions such as antimony(III), bismuth(III), lead(II), thallium(I), copper(II), nickel(II), etc. The method was extended for determination of tin in real samples.     

Special features of photolytic transformation of tin heteropolymetallic catecholate complexes

The photolysis of bis(dicarbonylcyclopentadienyliron)(3,6-di-tert-butylcatecholato)tin(IV), bis(dicarbonylcyclopentadienylmolybdenum)(3,6-di-tert-butylcatecholato)tin(IV), and bis(dicarbonylcyclopentadienyltunsten)(3,6-di-tert-butylcatecholato)tin(IV) in solutions of saturated hydrocarbons was studied. Kinetic parameters of the transformation of these compounds under the action of a monochromatic radiation with a wavelength of 313 nm were determined. Products of their transformation formed in the course of the irradiation were identified, and the probable mechanism of their photodecomposition was proposed.     

SYNTHESIS AND CHARACTERISATION OF TIN(IV) AND ORGANOTIN(IV) COMPLEXES OF [N′-2-HYDROXYPHENYL-6-METHYLPYRIDINE-2-CARBALDIMINE. X-RAY CRYSTAL STRUCTURES OF n-BUTYLDICHLORO[N′-2-HYDROXYPHENYL-6-METHYLPYRIDINE-2-CARBALDIMINATO(1-)N,N′,O]TIN(IV) AND DIPHENYLCHLORO [N′-2-HYDROXYPHENYL-6-METHYL-PYRIDINE-2-CARBALDIMINATO(1-) N,N′,O]TIN(IV)

Abstract

The reactions of N′-2-hydroxyphenyl-6-methylpyridine-2-carbaldimine (LH) with tin(IV) chloride and organotin(IV) chlorides result in the formation of the corresponding tin(IV) and organotin(IV) complexes in which LH behaves as a uninegative tridentate ligand coordinating to the central tin atom via an N,N,O donor set. Crystal structure determinations of two of the compounds, n-butyldichloro[N′-2-hydroxyphenyl-6-methylpyridine-2-carbaldiminato(l-)N,N′,O]-tin(IV) (BuSnCl₂.L) and diphenylchloro[N′-2-hydroxyphenyl-6-methylpyridine-2-carbaldiminato(l-)N,N′,O]tin(IV) (Ph₂SnCl.L), have been performed and both structures feature distorted octahedral geometries about the tin centres. Systematic differences in the Sn-ligand separations are rationalised in terms of the reduced Lewis acidity of tin in Ph₂SnCl.L.     

(Salen)tin complexes: syntheses, characterization, crystal structures, and catalytic activity in the formation of propylene carbonate from CO(2) and propylene oxide

A series of (salen)tin(II) and (salen)tin(IV) complexes was synthesized. The (salen)tin(IV) complexes, (salen)SnX(2) (X = Br and I), were prepared in good yields via the direct oxidation reaction of (salen)tin(II) complexes with Br(2) or I(2). (Salen)SnX(2) successfully underwent the anion-exchange reaction with AgOTf (OTf = trifluoromethanesulfonate) to form (salen)Sn(OTf)(2) and (salen)Sn(X)(OTf) (X = Br). The (salen)Sn(OTf)(2) complex was easily converted to any of the dihalide (salen)SnX(2) compounds using halide salts. All complexes were fully characterized by (1)H NMR spectroscopy, mass spectrometry, and elemental analysis, while some were characterized by (13)C, (19)F, and (119)Sn NMR spectroscopy. Several crystal structures of (salen)tin(II) and (salen)tin(IV) were also determined. Finally, both (salen)tin(II) and (salen)tin(IV) complexes were shown to efficiently catalyze the formation of propylene carbonate from propylene oxide and CO(2). Of the series, (3,3',5,5'-Br(4)-salen)SnBr(2), 3i, was found to be the most effective catalyst (TOF = 524 h(-)(1)).     

Structural investigation of dibenzyltin(IV) complexes of carbohydrates

Dibenzyltin(IV) complexes of carbohydrate derivatives were prepared and studied by Mössbauer and FTIR spectroscopy and by thermogravimetry. The Mössbauer studies indicated that the reaction between dibenzyltin(IV)-dichloride and sugar-type ligands led to reaction products containing tin(IV)-oxide. beside the dibenzyltin(IV) sugar complex. These two type of species were shown to be in weak interaction. Comparison of the experimental quadrupole splitting values with those calculated on the basis of the partial quadrupole splitting concept revealed the steric arrangements of the coordination sphere of tin(IV) in the sugar complexes.     

Stereoselective addition of diorganyl chalcogenides to cyclohexene catalyzed with tin(IV) chloride

The addition of diorganyl disulfides and dimethyl diselenide to cyclohexene in the presence of tin(IV) chloride proceeded stereoselectively affording trans-adducts of 1:1 composition. No reaction occurs in the absence of tin(IV) chloride.     

Synthesis and characteristic studies of tin(II) and tin(IV) complexes of macrocyclic schiff bases

Equimolar reactions of tin (II) chloride, tin(IV) chloride or dimethyltin dichloride with macrocyclic Schiff bases lead to the formation of a new series of tin(II) and tin(IV) complexes. An attempt has been made to prove the structures of the resulting complexes on the basis of elemental analysis, conductance measurements, molecular-weight determination, and electronic, IR and multinuclear magnetic resonance (¹H, ¹³C and ¹¹⁹Sn) spectral studies.     

Synthesis of homopolymers and block copolymers of methyl methacrylate and styrene in the presence of bis(3,6-ditert-butylcatecholato)tin(IV) ditetrahydrofuranate

The specific features of synthesis of poly(methyl methacrylate) and polystyrene in the presence of bis(3,6-ditert-butylcatecholato)tin(IV) ditetrahydrofuranate were studied. It was found that the catecholate tin complex can efficiently influence both the kinetic parameters of radical polymerization of the monomers and molecular mass characteristics of the product polymers. With the use on macroinitiators obtained in the presence of bis(3,6-ditert-butylcatecholato)tin(IV) ditetrahydrofuranate, block copolymers were synthesized.     

Layered microporous tin(IV) bisphosphonates

This article reports the hydrothermal synthesis and characterization of two new series of porous tin(IV) phosphonophenoxyphenylphosphonates with controlled pore size distributions, using as precursor the 4-(4'-phosphonophenoxy)phenyl phosphonic acid, [H2O3P-C6H4]2-O. Supermicroporous solids (S(BET), 300-400 m2 g(-1)) were obtained employing n-alcohol (C1-C6)-water mixtures (solvents ratio 1 : 1), in the presence of hydrofluoric acid. X-Ray powder diffraction shows that these compounds are semi-crystalline and the local environments around the phosphorus and tin elements have been studied by 31P and 119Sn MAS-NMR spectroscopy, respectively. The microstructure (particle sizes and shapes) of these phosphonates has been analyzed by scanning and transmission electron microscopy. This study shows that the microstructures of single-ligand (for instance tin(IV) phenylphosphonate) and cross-linked tin(IV) bisphosphonates are different. Tin(IV) phenylphosphonate crystallizes as micron-sized spheres, theta approximately 1-2 microm, formed by the aggregation of nanospheres, whereas tin(IV) bisphosphonates crystallize as microparticles larger than 20 microm. The textural properties of these porous solids were characterized by N2 and CO2 sorption isotherms. The key result of this work is that maxima of pore size distributions smoothly shift from 12 to 16 angstroms upon increasing the chain length of the alcohol. The microporosity of tin(IV) bisphosphonates is compatible with a double role played by the phosphonate groups acting as a pillar between adjacent layers and as a component of the hybrid organic-inorganic layers.