A new method for selective preconcentration of tin

In this paper the method of co-precipitating 10 g of Sn(IV) with Be(II) from an ammoniacal medium is made highly selective by incorporating a ternary masking system: (a) NH₂OH-NTA-EDTA or (b) H₂O₂-NTA-EDTA. It serves to preconcentrate Sn(IV) from a number of ionic species, especially from Nb(V), Ta(V) and Ti(IV) in mg or even cg amounts. System (a) is also effective for masking Th(IV) and U(IV), and (b) for Sb(III), Sb(V) and Ge(IV). Hence the two systems are complementary.     

Degradation mechanism of mixed nanostructured tin and titanium oxides when cycled

In order to study the nature of the degradation of thin-film electrodes consisting of nanostructured tin and titanium oxides (electrodes ST) and throw light upon the role played by processes with the oxygen participation, investigations of the phase composition in the electrodes that worked continuously in a charge-discharge regime and in forced-oxidation conditions are performed. It is confirmed that there exist two phases of degradation of electrodes when cycled. It is established, with the aid of the x-ray diffraction and Moessbauer analysis methods, that even short-term oxidation of electrodes by oxygen of air leads to the effect of “accelerated aging.” It is shown that, as the electrodes undergo aging both in the normal regime that rules out contact of the electrodes with air and in the course of the accelerated aging, there occurs irreversible accumulation of various modifications of SnO₂, including nanoareas of Sn⁴⁺-O (SnO₂ I), which are identical, with regard to electronic parameters, to classic semiconductor SnO₂, which has a high resistance. It is precisely the accumulation of the phase SnO₂ I that is responsible for the relatively fast degradation of the ST electrodes in a second phase of the cycling process.     

UV spectroscopy of metal volatilization during thermal plasma processing of waste glass melts

Atomic emission spectroscopy (AES) is used to monitor volatilization during waste vitrification with thermal plasmas. Model baste specimens consist of am alumino-silicate clay spiked with 10 wt. % Fe, Ni, or Cr. Specimens are vitrified in processing atmospheres with 0, 8.5, and 17 vol. % oxygen/argon concentrations. Particulate generated from condensation of the volatilized materials is collected following each specimen run and analyzed by energy dispersive X-ray analysis to determine composition. Spectra are collected from the ultraviolet range 240–380 nm in where the presence of metal vapor is readily detected. Correlation between line emission intensities and volatilization rates allows the establishment of provisional detection limits for the volatilization of Ni, Cr, Si, and Fe, of 1 × 10³ g/s, 4 × 10⁴ g/s, 2 × 10⁴ g/s, and 5 × 10⁵ g/s, respectively. The results of this investigation support the concept of using AES as an in-situ process monitor for feedback to optimize plasma processing of hazardous metal-containing waste.     

Hypersensitivity and its application to structural analysis of lanthanide complexes

Hypersensitivity of the ternary complexes Ln(β-dik)4HMQ(where Ln=Nd, Ho, Er,β-dik=acetylacetonate(AA), dibenzoylmethanate(DBM) and MQ=4-methylquinoline) in acetone solution is studied based on the dynamic coupling model. The structures of these complexes in solution are deduced. Their coordination polyhedrons are all distorted square antiprism. Neodymium complexes have D2 symmetry, while holmium and erbium complexes have exact D2d symmetry.     

Nucleophilic cyclocarbenes as ligands in metal halides and metal oxides

The nucleophilic cyclocarbene 1,3-dimethylimidazolin-2-ylidene (1) reveals universal ligand properties in metal coordination chemistry: in addition to the well-known stabilization of low oxidation-state transition metal fragments, this particular class of carbenes also coordinates with metal halides and metal oxides thus resembling the properties of conventional ether (O), amine (N), and phosphane (P) ligands. Complexes of titanium(IV), zirconium(IV), hafnium(IV), vanadium(II), niobium(IV), tantalum(IV) of general formula MX_nL_m (3a–f) and the rhenium(VII) of formula CH₃ReO₃L₂ (3g) are reported (L = 1,3-dimethylimidazolin-2-ylidene).     

N → Sn coordination in the complexes of tin halides with pyridine: A comparison between Sn(II) and Sn(IV)

The experimentally well‐known complexation of tin(II) and tin(IV) halides with pyridine (py) leads to structures showing N → Sn coordination. In the present work, the complexes SnX_n·mpy (where X = F, Cl, Br, I; n = 2, 4; m = 1, 2) possessing this kind of coordination were studied using a computational quantum chemical approach. Various aspects in the theoretical picture of these complexes were examined to find similarities and differences in their N → Sn coordination. The aspects included, among others, the physical nature of intermolecular interactions, and their role in establishing the structure and energetic stabilization of the complexes. In this context, the effect of tin valency was inspected in great detail. As proven by several theoretical methods, a largely ionic character with a certain covalent component can be attributed to the studied N → Sn coordination, irrespective of tin valency. All complexes are destabilized by py‐py and three‐body interactions, but the Sn(II) complexes experience it to a greater extent. Marked differences are observed in the structural behavior of N → Sn and SnX_n during complex formation. This affects the energetics of complexation and, in consequence, the penta‐coordinated Sn(IV) center shows a higher propensity to expand its coordination number, compared with the tri‐coordinated Sn(II) center. The present study supplements the experimental characterization of SnX_n·mpy and, in general, it sheds light on the coordination of heteroaromatic nitrogen to tin. The survey of the Cambridge Structural Database revealed that such coordination occurred in a number of crystal structures.     

Gravimetric determination of tin with sodium cyclotetramethylenedithiocarbamate and its applications in metal analysis

A gravimetric determination of tin is proposed with sodium cyclotetramethylenedithiocarbamate as precipitant at pH 5.0–5.5. By optimizing the reaction conditions the theoretical conversion factor 0.1687 can be used for determining ≥5% of Sn. Its standard deviation (n=10) at the level of 20 mg of Sn was found to be 0.08 mg. Effects of diverse cationic species can be eliminated by a clear-cut group precipitation at pH 9 with DDTC in the presence of tartrate and subsequent masking with EDTA. Provision is also made for removal of individual species in occasional cases. Hence, the proposed method is flexible and versatile and was successfully applied to the macro-determination of Sn in diverse alloys.     

Iron powder and tin/tin chloride as new reducing agents of Meerwein arylation reaction with unexpected recycling to anilines

Abstract

Simple and rapid route for Meerwein arylation reaction using iron powder or a mixture of tin/tin chloride has been developed. In the presence of iron powder, different aryl diazonium salts reacted with methyl vinyl ketone, acrylates, and isopropenyl acetate. Production of oximes was detected as the main product with acrylates or in a mixture with β-aryl methyl ketones in the case of methyl vinyl ketone. The in situ produced HNO₂ from an excess of NaNO₂/HCl was trapped by alkyl aryl radical to form oximes in the E configuration form. The presence of tin/tin chloride mixture in the reaction of the aryl diazonium salts with methyl vinyl ketone produced Michael products along with β-aryl methyl ketones. The predicted α-aryl methyl ketones from the reaction of isopropenyl acetate with the diazotized anilines were obtained using iron or tin/tin chloride mixture.     

Dynamics of hexafluoroanions in complexes of tin and titanium with mixed alkaline metal cations

Dynamics of anions in LiMSnF₆ and NaMTiF₆ (M=K, Rb, Cs) are studied in the temperature range 170–400 (470) K. Types of internal mobility of anions are established, anion activation energies are estimated, and effects on the activation barrier are discussed. Institute of Chemistry, Far East Branch, Russian Academy of Sciences. Translated fromzhurnal Strukturnoi Khimii, Vol. 39, No. 1, pp. 61–65, January–February, 1998.     

Study of interferences in the iodometry of tin its application to ore analysis

The mterference of molybdenum when tin is determined by rodate titration after reduction by aluminium, has been studied. A similar study was made of solutions also containing iron, and it was concluded that the interference in these solutions is almost non-existent. The results are discussed. A modified method for tin determination in ores containing molybdenum was proposed.     

Breakage of λ-DNA by inorganic tin and organotin compounds as environmental pollutants

In proportion to the environmental pollution problems caused by organotin compounds, the genotoxicities of tin compounds in the environments have become of interest so as to estimate their safety in recent years. In this work, isolated λ-DNA (double-strand DNA) was incubated with inorganic tin(II) and tin(IV) and five organotin compounds [n-butyltin trichloride, di(n-butyltin) dichloride, methyltin trichloride, dimethyltin dichloride and trimethyltin chloride] in reaction systems both with and without hydrogen peroxide (H₂O₂) content. The tin compounds tested in this study did not induce DNA breakage in the absence of hydrogen peroxide. Divalent inorganic tin (SnCl₂) and tetravalent inorganic tin (SnCl₄) caused DNA breakage in the presence of hydrogen peroxide (10 mM), and the DNA damage activity of inorganic tin was much more potent in divalent inorganic tin (SnCl₂) than in tetravalent inorganic tin (SnCl₄). Divalent inorganic tin (SnCl₂) induced DNA breakage in a concentration-dependent fashion at concentrations greater than 0.1 mM of SnCl₂ in the presence of hydrogen peroxide (10 mM). DNA breakage was not caused by n-butyltin compounds and methyltin compounds either in the presence or in the absence of hydrogen peroxide.     

三(邻溴苄基)溴化锡和四(对溴苄基)锡的合成及结构研究

邻溴苄基溴或对溴苄基溴与锡反应合成三(邻溴苄基)溴化锡(1)和四(对溴苄基)锡(2).经X射线方法测定了新化合物的晶体结构.晶体结构1属斜方六面体晶系,空间群为R-3,晶体学参数:a=1.3389(3) nm, b=1.3389(3) nm, c=2.1896(8) nm, V=3.3993(16) nm3, Z=6, Dx=2.077 Mg·m-3, μ(Mo Kα)=81.83 cm-1, F(000)=2004, R1=0.0477, wR2=0.1372;晶体结构2属正交晶系,空间群为Fdd2,晶体学参数:a=2.1027(7) nm, b=2.3034(8) nm, c=1.1431(4) nm, V=5. 536(3) nm3, Z=8, Dx=1.917 Mg·m-3, μ(Mo Kα)=67.11 cm-1, F(000)=3056, R1=0.0358, wR2=0.0659.化合物1中Sn-C键长为0.2160(8) nm, Sn-Br键长为0.2491(3) nm;化合物2中Sn-C键长分别为0.2175和0.2178 nm.中心锡与亚甲基碳(或溴)原子构成畸型四面体.     

Synthesis and physicochemical study of hexafluorocomplexes of tin with mixed alkali metal cations

Conclusions Hexafluorocomplexes of tin with mixed cations of alkali metals with the composition NaMSnF₆ (M=K, Rb, Cs) and crystallizing in the orthorhombic system have been synthesized for the first time from aqueous solutions. The parameters of the unit cells of these substances have been determined.The compounds synthesized are optically positive biaxial crystals; their optical and x-ray diffraction constants are given.In the IR spectra of all the fluorocomplexes synthesized a splitting is observed in the frequency of the stretching vibration (₃) for the octahedral anion SnF₆ ^2–.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 1927–1931, September, 1987.     

Application of galvanic stripping analysis to trace determination of tin

A simple, rapid and reliable procedure for the determination of tin by galvanic stripping analysis is described. The determination includes (i) preconcentration of tin onto preformed mercury film glassy carbon electrode, and (ii) re-oxidation in open-circuit position by advantageously utilizing the localized galvanic couple formation (in the absence of external electrical field or oxidant in solution). The details of the development of such a procedure and its application to the determination of tin in pure zinc materials are discussed.     

三(邻氟苄基）氯化锡和四(对氟苄基）锡的合成及结构研究

邻氟苄基氯或对氟苄基氯分别与锡反应合成三(邻氟苄基)氯化锡(1)和四(对氟 苄基)锡(2)．经X射线方法测定了新化合物的晶体结构．晶体结构1属单斜晶系，空 间群为P2(1)／n，晶体学参数：a＝0.5896(9)nm,b-1.262(2)nm,c=2.634(4)nm, V=1.959(5)nm^3,Z=4,Dx=1.632g/cm^3,μ（Mo Kα)=14.69cm^-1,F(000)=952, R1=0.0541,wR2=0.1280;晶体结构2属单余晶系，空间群为Cc,晶体学参数：α=1. 0778(6)nm,b=2.3312(14)nm,c=1.0888(7)nm,V=2.460(3)nm^3,Z=4,Dx=1. 499g/cm^2,μ(Mo Kα)=10.82cm^-1,F(000)=1112,R1=0.0302,wR2=0.0590.在化合 物1和2中Sn-C键长分别为0.2136-0.2148和0.2138-0.2180nm,Sn-Cl键长为0.2378 (4)nm,中心锡与亚甲基碳（氯）原子构成畸型四面体。     

Sn(I) halides: Novel binary compounds of tin and their application in synthetic chemistry

Metalloid cluster compounds are ideal model compounds for the area between the molecular and solid state, i.e. the nanometer regime. For the synthesis of metalloid cluster compounds, the disproportionation reaction of a metastable subhalide is a fruitful synthetic route. In the case of tin, monohalides are needed for this synthetic route as tin(II) halides are too stable to be used. Due to thermodynamic data, gaseous SnBr should be formed at 1370 °C, and by applying a co-condensation technique it can be trapped at −196 °C and prepared in synthetic scale. Herein first analyses of SnBr are presented, showing that SnBr is more reactive than the corresponding GeBr, already disproportionating quantitatively to elemental tin and SnBr₂ on heating to room temperature. By applying nitrogen-based donor molecules like NnBu₃ or pyridine, the reactivity can be moderated and the solubility is enhanced leading e.g. to an SnBr emulsion, which can be used for the synthesis of metalloid cluster compounds of tin.     

三(3,5-二甲基苄基)氯化锡和四(间氰基苄基)锡的合成、晶体结构和量子化学研究

以3,5-二甲基苄基氯和间氰基苄基氯在适当的溶剂中与锡粉反应,合成了三(3,5-二甲基苄基)氯化锡(1)和四(间氰基苄基)锡(2),经X射线衍射方法测定了化合物的晶体结构。化合物1属单斜晶系,空间群为P21/m,晶体学参数:a=0.584 03(4)nm,b=1.966 37(14)nm,c=0.856 46(5)nm,β=95.138(3),V=0.979 62(11)nm3,Z=2,Dc=1.735 g·cm-3,μ(Mo Kα)=14.53 cm-1,F(000)=524,R1=0.043 7,w R2=0.123 2。化合物2属单斜晶系,空间群为C2/c,晶体学参数:a=1.692 21(12)nm,b=1.167 41(8)nm,c=1.539 41(11)nm,β=116.615(10)°,V=2.718 9(3)nm3,Z=4,Dc=1.424 g·cm-3,μ(Mo Kα)=9.67cm-1,F(000)=1 176,R1=0.017 5,w R2=0.046 1;中心锡原子为畸变四面体构型。对其结构进行量子化学从头计算,探讨了配合物的稳定性、分子轨道能量以及部分前沿分子轨道的组成特征。     

三(邻甲基苄基)锡和二(间氟苄基)锡硫代水杨酸酯配合物的合成、结构及性质

合成了三(邻甲基苄基)锡硫代水杨酸酯配合物(1)和一维链状二(间氟苄基)锡硫代水杨酸酯配合物(2),经元素分析、IR、NMR、X射线衍射等技术手段表征了其结构。配合物1属三斜晶系,空间群Pī,晶体学参数a=1.00221(5)nm,b=1.48934(8)nm,c=1.71789(9)nm,α=78.3120(10)°,β=85.6560(10)°,γ=80.2580(10)°,V=2.4725(2)nm~3,Z=2,Dc=1.371 g/cm~3,μ(Mo Kα)=10.91 cm~(-1),F(000)=1040,R_1=0.0439,wR_2=0.1119。配合物2属单斜晶系,空间群为P21/n,晶体学参数:a=1.17827(5)nm,b=2.11945(9)nm,c=1.55970(7)nm,β=93.4510(10)°,V=3.8880(3)nm~3,Z=4,Dc=1.671 g/cm~3,μ(Mo Kα)=14.53 cm~(-1),F(000)=1936,R1=0.0323,wR2=0.0927。配合物1中锡原子呈四配位畸变四面体构型,配合物2中锡原子呈五配位畸变三角双锥构型。配合物1和2分别在152和195℃下稳定,电化学性质不可逆,对人体癌细胞Colo205、Hep G2、MCF-7、Hela和NCI-H460具有体外抗癌活性,配合物2的抗癌活性远大于配合物1。     

三(3,5-二氟苄基)氯化锡和四(邻氯苄基)锡的合成、晶体结构及量子化学

3,5-二氟苄基氯和邻氯基苄基氯在适当的溶剂中与锡粉反应,合成了三(3,5-二氟苄基)氯化锡(1)和四(邻氯苄基)锡(2),经X射线衍射方法测定了新化合物的晶体结构。化合物1属单斜晶系,空间群为C2/c,晶体学参数:a=1.858 33(11)nm,b=1.140 98(7)nm,c=2.690 06(16)nm,β=109.288(10)°,V=5.383 6(6)nm3,Z=8,Dc=1.532 g·cm~(-3),μ(Mo Kα)=13.61 cm~(-1),F(000)=2 480,R1=0.085 1,wR~2=0.168 1。化合物2属单斜晶系,空间群为P21/m,晶体学参数:a=0.585 54(5)nm,b=1.969 74(18)nm,c=0.857 86(8)nm,β=95.204 0(10)°,V=0.985 34(15)nm3,Z=2,Dc=1.805 g·cm~(-3),μ(Mo Kα)=14.91 cm-1,F(000)=524,R1=0.054 0,wR_2=0.163 9;中心锡原子为畸变四面体构型。对其结构进行量子化学从头计算,探讨了化合物的稳定性、分子轨道能量以及部分前沿分子轨道的组成特征。测定了化合物的热稳定性。     

金属锡和三甲基氯硅烷存在下芳香醛、酮与醇的还原-偶联-醚化 反应

在三甲基氯硅烷(TMSCl)、四氢呋喃(THF)体系中,芳香醛、酮和醇在金属锡的作用下发生还原-偶联-醚化反应生成相应的频那醇二醚类化合物。文中对此反应的应用范围进行了探讨,并提出了合理的反应机理。