Tetravalent Tin Research Articles

On the behaviour of tin-containing species in cryolite–alumina melts

Tin oxide (SnO2) dissolves in cryolite–alumina melts forming tetravalent tin species, but under reducing conditions it is reduced to divalent tin and, further, to metallic tin. Freezing point depression data for SnF2 and SnO in molten cryolite (Na3AlF6) corresponded to the formation of one and two new particles, respectively. By anodic dissolution of tin into cryolite-alumina melts divalent as well as tetravalent tin was formed, depending on current density and composition. During electrolysis of SnO2-based oxygen-evolving anodes, the condensate above the melt contained both divalent (SnF2) and tetravalent (SnO2) tin species.

Oxidation–reduction alternating copolymerization of stannylenes with p‐benzoquinone derivatives

AbstractStannylenes, bis[bis(trimethylsilyl)amido]tin(II) (1) and bis[bis(trimethylsilyl)methyl]tin(II) (2), have been copolymerized with p‐benzoquinone derivatives to afford a novel class of tin‐containing polymers (4 and 5) having a tetravalent tin unit and a p‐hydroquinone unit alternatingly in the main chain. The oxidation state of the stannylenes changes from two to four while the p‐benzoquinone moiety is reduced to the corresponding p‐hydroquinone unit, indicating that the copolymerization proceeds via a redox process (oxidation‐reduction copolymerization). Some of the resulting copolymers are stable at room temperature and soluble in common organic solvents such as chloroform and n‐hexane. The molecular weight (Mw) of the resulting copolymers was in the range of 1.1 x 105 to 4.9 x 103.

Oxidation of SnF2 stannous fluoride in aqueous solutions

The rate of oxidation of SnF2 in aqueous solutions has been studied by redox titrations and Mossbauer spectroscopy on frozen solutions versus the acidity of the solutions and versus time. Tin(II) oxidizes in aqueous solutions; however, the rate of oxidation is much slower than previously reported. Redox titrations show that the amount of tetravalent tin increases continuously with time. Oxygen dissolved in water seems to be the oxidizing species. The oxidation rate is faster in acidic solutions. Mossbauer spectroscopy on frozen solutions shows the slow formation of tetravalent tin; it also indicates that divalent tin in aqueous solutions is similar to that observed in solid SnF2, except that one water molecule coordinates tin.

Crystal structure and Mössbauer spectroscopic study of FeSnF6·6H2O

Large single crystals of FeSnF6·6H2O were grown when aqueous hydrofluoric solutions of SnF2 and FeF2 were allowed to evaporate in air. Tin-119 Mossbauer spectroscopy at ambient temperature shows a single line at slightly negative isomer shift relative to CaSnO3 at room temperature (δ=−0.380(6) mm/s, Δ=0). This is characteristic of tetravalent tin octahedrally coordinated by fluorine. The X-ray crystal structure shows that tin(IV) is coordinated by 6 fluorine atoms, and Fe(II) by 6 water molecules. Both sites show a slight distortion from octahedral symmetry: the six distances are equal (Sn-Fe=1.941(3) A and Fe-O=2.112(3) A), whereas there are two values of angles (Fe-Sn-F=90.4(1)° and 89.6(1)°; O-Fe-O=91.1(1)° and 88.9(1)°). The material is an ionic compound [SnF6]2−[Fe(H2O)6]2+.

From .sigma.- to .pi.-bonding: crystal structures of (pentamethylcyclopentadienyl)triiodostannane and dichloro(pentamethylcyclopentadienyl)stibine

Cyclopentadienyl compounds of the tetravalent group 14 elements and of the trivalent group 15 elements are characterized by their dynamic behavior due to migration processes of the relevant ElR, fragment. As shown by experiments and calculations, the energy difference between the [sigma]-ground state and the [pi]-transition state in these molecules becomes smaller on going to the heavier elements and on exchanging halogen atoms for organic ligands. Thus, Cp compounds of tetravalent tin or lead and of trivalent antimony or bismuth bearing halogen ligands should be suitable candidates for the realization of a [pi]-ground state. In this context, we have investigated the solid-state structure of the title compounds Me5C5SnI3 (1) and Me5C5SbCl2 (2) by X-ray crystallography. It is shown that in the tin compound 1 the main-group fragment is still [sigma]-bonded, whereas [pi]-bonding is observed for the antimony compound 2. The bonding parameters for 1 and 2 are discussed with those of other tin, lead, antimony, or bismuth Cp compounds from the literature. Crystal data with Mo K[alpha]([lambda] = 0.71073 A) radiation are as follows: 1, a = 8.044 (2) A, b = 15.094 (2) A, c = 13.907 (2) A, [beta] = 102.43 (2)°, Z = 4, monoclinic, space group P21/n, Rw = 0.050; 2, a = 10.479 (2) A, b = 8.384 (2) A, c = 14.101 (3) A, [beta] = 94.50 (2)°, Z = 4, monoclinic, space group P21/a, Rw = 0.068.

Anion Selectivity of Tetravalent Tin Compounds in Membranes Studied by 119Sn‐, 13C‐ and 1H‐NMR

AbstractThe fundamental molecular aspects of trialkyltin compounds of the type R3SnY have been investigated in view of their applicability as ion‐selective components in solvent polymeric membranes. The interaction between these compounds and anions has been studied using 119Sn‐ and 13C‐NMR. Neutral tetracoordinated trialkyltin compounds form a negatively charged pentacoordinated complex upon interaction with Cl‐ions in homogeneous organic phases as well as in membranes in contact with aqueous solutions. Although in a homogeneous phase, the electronegative substituent Y determines the complex‐formation constant, it has no influence on the potentiometric anion selectivity in liquid membranes containing trialkyltin carriers R3SnY with different Y. The observed selectivity pattern is not given by the magnitude of the stability constants in a homogeneous phase but is dictated by the prevailing association‐dissociation process leading to tetracoordinated compounds which change in constitution due to varying sample composition, The results obtained from equilibrium studies of tetravalent mono tin compounds with anions in both homogeneous phase and in two‐phase systems confirm the earlier hypothesis that trialkyltin compounds incorporated in solvent polymeric membranes act as electrically neutral carriers for anions.

The Mössbauer effect of SnI4 at high pressures

Tetravalent tin iodide is a molecular crystal composed of SnI4 tetrahedra loosely packed into a cubic configuration. Under pressure SnI4 becomes metallic at about 15 GPa. We report a Mossbauer effect study of119Sn and129I in SnI4 to pressures of 26 GPa. The spectra exhibit dramatic changes with pressure starting at about 10 GPa and show large pressure hysteresis effects upon reducing the pressure from 26 GPa. In the intermediate region tin exists in both Sn4+ and Sn2+ states, and iodine exists in two nonequivalent sites characterized by a different symmetry and different sign and magnitude of the electric field gradient.

2,3-Dimethyl-1-ethyl-1,2,3-aluminadicarbadodecaborane; a versatile carbollyl transfer reagent

2,3-Dimethyl-1-ethyl-1,2,3-aluminadicarbadodecaborane, prepared from triethyl-aluminum and 7,8-dimethyl-7,8-dicarbadodecaborane, has been shown to be a useful precursor for the synthesis of icosahedral main-group carboranes. The electrophilicity of the aluminum atom, which is illustrated by the formation of adducts with diethyl ether and tetrahydrofuran, enables the compound to undergo substitution reactions with nucleophiles. Whereas conversion with methylboron dibromide, germanium diiodide, or tin dichloride yielded the corresponding methylboron-, germanium- and tin-substituted icosahedrons, treatment with trimethyltin chloride or dimethyltin dichloride gave 1,1,2,3-tetramethyl-1,2,3-stannadicarbadodecaborane, apparently the first metalladicarbadodecaborane containing tetravalent tin.

Cyclische Diazastannylene, IV1 Zur Oxidation von 1.3-Di-tert-butyl-2.2-dimethyl-1.3.2.4λ2 -diazasilastannetidin / Cyclic Diazastannylenes, IV1 Oxidation of 1,3-Di-tert-butyl-2,2-dimethyl-1,3,2,4λ2 -diazasilastannetidine

Abstract The reactions of 1,3-di-tert-butyl-2,2-dimethyl-1,3,2,4λ2-diazasilastannetidine (1) with O2 and S8 or SnCl4 proceed in two steps: In a first redoxtype reaction an intermediate containing tetravalent tin is formed. Some of these intermediates are unstable with respect to the starting material stannylene 1 and undergo a substitution reaction to yield a spirotetraazastannane. Under appropriate conditions the intermediate from the sulfur- and SnCLi- reaction can be isolated and turns out to be either dispiro[3,3,3]distanna-disulfadisila- tetrazane or a diaza-dichlorostannane respectively. Crystal and kinetic data of some products/reactions are reported.

Dynamic nuclear polarization of tin-119 nuclei in free radical solutions

Dynamic nuclear polarization of tin-119 in free radical solutions has been studied at 175 G. Scalar interactions are predominant for both bivalent and tetravalent tin compounds.

The determination of tin in rocks by thermal neutron activation

A fast routine method for the determination of tin in rocks is discussed. The method is based on coprecipitation of tetravalent tin with ferric hydroxide, followed by a short irradiation in a high thermal neutron flux, extraction in toluene from 1∶1 sulphuric acid which is 5N in potassium iodide, and counting of123mSn (T=40 m) or125mSn (T=9.7 m) with a well-type NaI detector. In the present work125mSn was used. The lower limit of determination is governed by the blank of the reagents. For a sample of at least one gram it is ≌ 0.2 μg Sn·g−1.

Polarographic studies on the N-benzoylphenylhydroxylamine complex of tin and pulse polarographic determination of trace quantities of tin after extraction

A polarographic investigation on the N-benzoylphenylhydroxylamine (BPHA) complex of tin has been made in a mixture of chloroform and methanol. From the studies it has been confirmed that the complex is formed by tetravalent tin. A tentative mechanism of the oxidation of tin(II) in presence of BPHA has been suggested. Moreover, a rapid, sensitive and specific method of determination of tin in trace quantities by derivative pulse polarography has been developed. The chloroform extract can be directly subjected to polarography after addition of requisite quantities of water and methanolic lithium perchlorate. Effect of different supporting electrolytes on the system has been studied. By the described method 7×10−7 M to 2×10−5 M tin can be determined without interference from large quantities of the elements commonly associated with tin and also from a large number of other elements and complexing agents.

Pyrophosphates of Tetravalent Elements and a Mössbauer Study of SnP2O7

Cubic M4+P2O7 pyrophosphates of Ti, Zr, Hf, Sn, and Pb have been examined by X-ray powder diffractometry and by infrared, Raman, and Mössbauer 119Sn spectroscopy. The tin compound appeared to be of Chaunac's type I (with P2O7 groups oriented at random) and could be converted to type II (with ordered P2O7 groups) by heating to high temperatures. All the other preparations were of Chaunac's type II. Evidence from lattice parameters and intensity features of the Raman spectra suggests that the cubic MP2O7 pyrophosphates fall in two groups, one containing the compounds of the typical elements (Ge, Sn, Pb) and the other, the compounds of the transition elements. No support has been found for the view that the P—O—P groupings of the pyrophosphate anion in these compounds are linear. The 119Sn chemical shift in SnP2O7 is only slightly less negative than the shift in CuSnF6.4H2O, which makes SnP2O7 one of the most ionic compounds of tetravalent tin known. The observed quadrupole splitting in the Mössbauer spectrum of SnP2O7 arises largely from the contribution of the valence term to the electric field gradient at the Sn atom.

Introduction, preliminary handling, and diseases of grass carp in New Zealand

Abstract Fry of grass carp, Ctenopharyngodon idella (Val.), were air‐freighted from Hong Kong to New Zealand in October 1971. The fish were at first kept in tanks with a recirculating water supply, where they soon showed symptoms of parasitic infestation and suffered heavy mortality. Attempts were made to remove parasites with chemotherapeutic treatment. Tripartiella sp., Dactylogyrus ctenopharyngodonis, and Gyrodactylus clenopharyngodontis were eliminated by prolonged bathing of the infected fish with quinine. Chemical treatment failed to eliminate Ichthyophthirius mullifiliis from the body surface and the gills, but the rate of spontaneous recovery of the fish from this disease was accelerated by keeping them in clean, running water. Experiments to remove the cestode Bothriocephalus gowkongensis from the intestine of the fish with tetravalent tin compounds and to control the intermediate host (Cyclops) in the water resulted in the eradiction of the cestode. When parasitic infestations had been brought under control the fish were transferred to outdoor ponds, where they began to feed on aquatic and terrestrial vegetation and rapidly increased in size.

The determination of tin in biological samples

A rapid method is described for the determination of tin in biological material, using123Sn (T=40 m). The chemical procedure is based on the nearly quantitative extraction of tetravalent tin into toluene from an acid 1.3M iodide solution. The recovery is determined by spiking the solution with113Sn and measuring the activity of the113mIn daughter in the counting sample. The lower limit of the determination is ≃0.01μg. Results are given for standard kale powder and dried animal blood.

Mössbauer Study of Tin(II) Sensitizer Deposits on Kapton

Mössbauer spectroscopy has been used to study tin(II) sensitizer deposits formed on Kapton films (du Pont polyimide) for use in the recently reported photoselective metal deposition (PSMD) process. Combined with previous results, this work shows that the sensitizer is present as a colloid in the sensitizing bath and is adsorbed on the substrate when it is dipped. This activation mechanism would be expected to apply to other insulating substrates as well. The photosensitive substance contains more tetravalent tin than divalent. The divalent tin is oxidized by exposure either to air or to the Pd activation bath. The photosensitive compound is not any well recognized tin oxychloride or hydroxide.

Crystal structure of a new octahedral complex of tetravalent tin

Crystal structure of a new octahedral complex of tetravalent tin

Isomer Shift and Electronegativity in Compounds of Tin and Group-VI Elements

Using the Mössbauer effect in 119Sn we have measured the isomer shift in compounds of divalent and tetravalent tin with elements of Group VI. The isomer shift is linearly dependent on the values of electronegativity in both series of compounds. The coefficient of this dependence is for tetravalent compounds nearly twice that of the divalent ones. This result is discussed in terms of electron structure of the chemical bonds of the compounds.

Orbital Populations and π Backbonding in Some Organohalostannanes: The Interpretation of Tin Mössbauer and Ligand NQR Data

Tin Mössbauer isomer shifts and quadrupole splittings are reported for 23 compounds. Equations are derived and applied which enable the tin hybrid orbital populations for tetravalent tin compounds of the type AmSnB4−m to be determined from the above data. Critical tests of the theory are proposed. A minimum value of 5.8 mm sec−1 is obtained for the quadrupole splitting due to one p electron by comparing Mössbauer-derived with ligand NQR-derived populations. The two sets of populations are also used to obtain π backbonding orbital populations in organohalostannanes. The results show that tin sp3 orbitals are more important than d orbitals for π backbonding.

Relation between the Electronic Structure of Tin in Its Compounds and the Isomer Shifts in Mössbauer Spectra

Expressions relating isomer shifts in Mössbauer spectra with the electronic structure of tin in its compounds are obtained. These expressions give a description of isomer shifts for chemical compounds of different types: tetravalent tin when there is π bonding (tin tetrahalogenides), tetravalent tin in the absence of π bonding (compounds where tin is bound with alkyl, aryl, and carbonyl metal radicals), bivalent tin, etc. The expressions obtained were used for analysis of the electronic structure of tin in compounds of these classes. For tetravalent tin compounds with π bonding the change of isomer shift δ towards negative values (with respect to α-Sn) is found to be accounted for by a decrease, and for compounds without π bonds by an increase in the number of valence 5s electrons (S) at S>1.