Mössbauer study of the Sn resonance in rare-gas matrix-isolated Sn(IV)-and Sn(II)halide molecules

Mössbauer absorption spectra of rare-gas matrix-isolated SnX₄ and SnX₂ molecules (X = F, Cl, Br, I) have been measured at matrix temperatures of a bout 5 K. The hyperfine interaction (hfi) parameters of ¹¹⁹Sn in argon matrix-isolated SnX₄ (X = Cl, Br, 1) molecules are identical with those of the corresponding crystalline compounds. This fact reveals that the inter-molecular interactions are negligible in the crystalline compounds as far as concerning the electronic structure of Sn⁴⁺. The ¹¹⁹Sn hfi parameters of rare-gas matrix-isolated SnX₂ molecules differ from those measured in the crystallin compounds. This arise from the totally different coordination of tin in the two situations. The analysis of the hfi parameters using a simple bonding model yields information about the ionicity of the Sn-halogen bonds and the bonding angle in these molecules. The observed isomer shifts and quadrupole interactions can only be explained in this model with a bonding angle θ = 95° ± 2° for all SnX₂ molecules and a slight increase of θ from Sn1₂ to SnF₂.     

Sn(3) and Sn(10) sulfonate-oxide-hydroxide clusters with two different sulfonate binding modes

A tin sulfonate-oxide-hydroxide tetracation with two different sulfonate bindings, an electrostatic and a monohapto covalent one, and a tin sulfonate-oxide-hydroxide monocation with two other kinds of sulfonate bindings, an electrostatic and a dihapto bridging one are described here.     

Complexes of Sn(II), Sn(IV), Pb(II) AND Bi(III) with selenourea

Conclusions Some new compounds of selenourea with Sn(II), Sn(IV), Pb(II) and Bi(III) were obtained, which had the composition: SnCl₂·2Seu, SnCl₄·4Seu, PbCl₂·2Seu, 2Pb(NO₃)₂·11Seu and Bi(NO₃)₃·6Seu.Deceased.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1556–1557, July, 1971.     

Luminescence in Zinc Selenide Doped with Sn and (Sn,Dy) Phosphors

Zinc selenide doped with Sn and (Sn, Dy) phosphors has been prepared by firing the samples in an atmosphere of nitrogen gas. The voltage and frequency dependence of electrolyte brightness has been studied. Voltage dependence of electroluminescence (EL) brightness reveals an acceleration collision mechanism in the Schottky barrier at the metal–semiconductor interfaces. EL and photoluminescence (PL) spectra and thermoluminescence (TL) glow curves of these phosphors have also been recorded to understand the nature and mechanism involved in the luminescence process. The trapping parameters are calculated for the glow curves of these phosphors.     

Enantiospecific Sn(II)- and Sn(IV)-catalyzed cycloadditions of aldehydes and donor-acceptor cyclopropanes

A cycloaddition strategy for the synthesis of highly enantioenriched 2,5-cis-disubstituted tetrahydrofurans has been developed. In the presence of catalytic Sn(OTf)2 or SnCl4, a range of aldehydes will undergo formal [3 + 2] cycloadditions with a scalemic donor-acceptor cyclopropane to form optically active heterocycles. Mechanistic studies support an unusual SN2 attack by the aldehyde on the activated cyclopropane. Through this mechanism, stereochemical information contained in the cyclopropane is effectively transferred to the tetrahydrofuran products.     

Li2Sn(OH)6

Hydro­thermally prepared dilithium tin hexa­hydro­xide crystallizes in the monoclinic system (space group P2₁/n), with the Sn atom at a site with symmetry and all other atoms in general positions. The Sn coordination polyhedron is made up of six hydro­xide groups. The Li atom is tetrahedrally coordinated by oxy­gen, with the tetrahedra sharing two corners and one edge with the adjacent Sn octahedra. Hydro­gen bonds between the OH groups provide additional bonds in the framework.     

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.     

Sn(x)Pt4Sn(y)Sb(12-y): a skutterudite with covalently bonded filler

A new phase, Sn(x)Pt4Sb(12-y)Sn(y), has been prepared from the elements. It exhibits a wide range of homogeneity with 0.3(2) < or = x < or = 1.0(2) and 4.2(2) < or = y < or = 7.0(2). The crystal structure and the composition were established by single-crystal and powder X-ray diffraction as well as wavelength-dispersive X-ray analysis measurements and were supported by nuclear magnetic resonance experiments. The compound is the first representative of the filled-skutterudite family with the filler atoms not located at the center of the cavity but covalently bonded to the cavity's wall, as confirmed by the analysis of chemical bonding with the electron localizability indicator. The Sn and Sb atoms share the framework site with different coordinate parameters caused by the difference in atomic size; additional tin atoms are located in the cavities of the framework. The material is a diamagnet in the whole composition range. In agreement with the calculated electronic density of states, the material reveals a metallic behavior in electronic transport. The absolute values of electrical resistivity vary with the tin-to-antimony ratio.     

Shelf-life of99mTc(Sn)-pyrophosphate

The effect of the preparation conditions on the in vitro stability of^99mTc (Sn)-pyrophosphate kit solution has been examined. To extend the shelf-life of the preparation, different methods of protection were tested. Nitrogen purging stabilizes the kit for at least 6 h after labeling when the content of^99mTc-pertechnetate raises to about 5%. However, this method is ineffective in the presence of hydrogen peroxide. The protecting ability of two chemicals was also determined. Gentisic acid gave good results. In the presence of 50 g of gentisic acid per ml of the kit the content of pertechnetate was 1–2% throughout the examined time interval. To eliminate the influence of hydrogen peroxide (6 g per ml of the kit) about 100 g of gentisic acid is needed. N, N-diphenyl-p-phenylenediamine (DPPD) performs some protecting effect only when used in the samples protected by nitrogen purging. However its protecting ability is lower that in the case of gentisic acid.     

Sn12(2-): stannaspherene

Stannaspherene. The Sn122- cluster is discovered to be a highly stable and highly symmetric icosahedral cage bonded by four delocalized radial pi bonds and nine delocalized on-sphere sigma bonds from the 5p orbitals of the Sn atoms. It has a diameter of 6.1 A, with a large empty interior volume, and can host most transition metal atoms inside, giving rise to a large class of endohedral chemical building blocks for cluster-assembled nanomaterials.     

Syntheses,characterization, and Mossbauer study of Sn(II and Sn(IV) complexes of the cyclopentadienedithiocarboxylate ligand

The preparation and physical characterization of the tetraethylammonium salts of bis(cyclopentadienedithiocarboxylate)stannate(II) and tris(cyclopentadienedithiocarboxylate)stannate(IV) are reported. The coupling constants for the ring protons of the coordinated and uncoordinated ligand indicate that the oxidation state variation of the metal has little effect on the electronic structure of the ligand. The Mössbauer parameters for the Sn(IV) complex (δ = 1.05 ± 0.02 mm/sec with respect to SnO₂, Line width = 1.05 mm/sec) are normal for a pseudo-octahedral complex. The values for the Sn(II) complex are somewhat abnormal for a Sn(II) complex (δ = 0.29 mm/sec, Line width = 1.65 mm/sec) and are interpreted as indicative of metalmetal bonding in the molecular structure.     

Combined X-ray diffraction and diffuse reflectance analysis of nanocrystalline mixed Sn(II) and Sn(IV) oxide powders

Nanocrystalline mixtures of Sn(II) and Sn(IV) oxide powders, potential gas sensor materials, are synthesized via a simple precipitation route using SnCl(2) as the precursor. Materials are characterized by powder X-ray diffraction, thermogravimetric analysis, UV-visible diffuse reflectance spectroscopy (DRS), and Fourier transform infrared spectroscopy. The ratio of Sn(II)/Sn(IV) in powders precipitated at room temperature, as well as the identity of the primary Sn(II) product (SnO or Sn(6)O(4)(OH)(4)), can be varied by adjusting aging time and washing procedures. The identity of the initial Sn(II) product influences the subsequent phase composition and degree of disorder in the tetragonal SnO(2) phase obtained following sintering in air. Analysis of the DRS absorption edge and long-wavelength (Urbach) absorption tail is used to determine the SnO(2) optical band gap and extent of disorder. SnO(2) obtained by heating the SnO/SnO(2) mixture at 600 or 800 degrees C has a smaller optical band gap and a broader Urbach tail than the analogous sample obtained from heating Sn(6)O(4)(OH)(4), indicating a more disordered material.     

Synthese und Strukturbestimmung von (tBuP)4Sn(CH3)2 und (CH3)2Sn[(tBu)P?P(tBu)]2Sn(CH3)2

Synthesis and Structure Analysis of (tBuP)₄Sn(CH₃)₂ and (CH₃)₂Sn[(tBu)P? P(tBu)]₂Sn(CH₃)₂ The diphosphides K₂[(tBu)P? (tBuP)₂? P(tBu)] 7 or K₂[(tBu)P? P(tBu)] 8 react with (CH₃)₂SnCl₂ in a molar ratio of 1 : 1 to form the binary 5-membered ring system P₄Sn 4 a and the 6-membered ring system Sn(P₂)₂Sn 5 a respectively. When (CH₃)₂SnCl₂, however, is treated with 8 in a molar ratio of 2 : 1 the 4-membered ring system P₃Sn 2 a is formed which includes the fragmentation of the intermediate K₂[(CH₃)₂Sn ((tBu)P? P(tBu))₂] 9. 4 a and 5 a could be obtained in a pure form and characterized NMR spectroscopically and by X-ray structure analyses; 2 a was identified only NMR spectroscopically.     

The transformation of Sn(ND3)2F4 into Sn(ND2)2F2. Synthesis and neutron crystal structure determination of Sn(ND2)2F2

Diamido-difluoro-tin Sn(ND₂)₂F₂ can be produced by ammonolysis from (NH₄)₂SnF₆ at 633 K. The compound is a product formed from Sn(ND₃)₂F₄ during the ammonolysis reaction. Sn(ND₂)₂F₂ isostructural with Sn(NH₂)₂F₂ crystallizes in space group C2/m with lattice constants a = 1072.92(7), b = 325.97(1) pm, c = 505.79(4) pm and β = 105.713(6) ° (V = 170.28(1) ·10⁶ pm³) containing two formula units per unit cell. Data refinement by the Rietveld method of neutron time-of-flight data collected at POLARIS yields a weighted profile R-value R_wp = 0.022. Tin is octahedrally coordinated by two fluorine atoms and four amido groups. The octahedra are connected to one-dimensional chains by edge sharing. The ND₂ groups are in the bridging position whilst the fluorine atoms are terminal. Nearly linear (175.2(4) °) and angular (134.35(8) °) N-D···F hydrogen linkages connect the chains.     

双异丙烯基二茂金属(Sn,Ti)的合成

虽然,廿多年来各同学者对二茂铁衍生物进行了深入的研究,但却极少报道合成二茂锡衍生物,仅见1959年Wilkinson等合成双甲熬二茂锡以及Cowley等合成(Me₃SiC₅H₄)₂Sn和[(i-Pr₂N)₂PC₅H₄]₂sn,二茂钛衍生物的报道较多,但除Rausch等报道过合成低产率的乙烯基二氯二茂钛(Ⅳ)外,几乎没有报道过类似的烯烃二茂钛(Ⅳ)的合成。     

Kristallstruktur von Cu10Sn3(m)

Zusammenfassung Cu₁₀Sn₃(m) hat eine hexagonale Struktur, die in enger Verwandtschaft zur Struktur des CuZn steht. Einer der Hauptunterschiede beider Strukturen ist eine Stapelvariation der Schichten parallel (111)_CuZn. Aus dieser folgen weitere Verschiebungen der Atome, so daß die Struktur auch als Variante der NiAs-Struktur beschrieben werden kann. Gründe für die Stapelvariation lassen sich aus Annahmen über die Ortskorrelation der Elektronen herleiten.

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Crystal structure of Cu₁₀Sn₃(m)

Cu₁₀Sn₃(m) has a hexagonal structure, which is closely related to the structure of Cuzn. One of the main differences of these structures is a stacking variation of the layers parallel (111)_CuZn, which implies further shifts of atoms so that the structure may also be described as a variant of the NiAs structure. Causes for the stacking variation may be derived from assumptions on the spatial correlation of the electrons.

     

(119/117/115)Sn low-abundance single-transition correlation spectroscopy (LASSY): sensitivity-enhanced homonuclear correlation experiments for Sn NMR

We report the implementation of our novel rare-spin homonuclear correlation experiment, namely, Low-Abundance Single-transition correlation SpectroscopY (LASSY), for (119/117/115)Sn NMR at natural abundance. Our pulse sequence results in diagonal suppressed COSY-style display and outperforms the optimal homonuclear correlation experiment for rare spins, which involves double quantum evolution (INADEQUATE CR). The new experiment maximizes efficiency both in respect of pulse transformations as well as relaxation effects, and gives rise to a simplified two-dimensional (2D) spectrum with considerably reduced crowding, exhibiting only one transition in each cross peak, instead of four. Performance optimization of LASSY is carried out in light of the relatively 'large' line widths typical of Sn NMR in solution state. The superior performance of the sequence is demonstrated on dimeric tetraorganodistannoxane samples.     

Tin(II) aminoalkoxides and heterobimetallic derivatives: the structures of Sn6(O)4(dmae)4, Sn6(O)4(OEt)4 and [Sn(dmae)2Cd(acac)2]2

Tin(II) methoxide reacts with N,N′‐dimethylaminoethanol (dmaeH) to yield Sn(dmae)₂ ( 1 ) along with small amounts of the hydrolysis product Sn₆(O)₄(dmae)₄ ( 2 ). The geometrically more regular iso‐structural cage Sn₆(O)₄(OEt)₄ ( 3 ) was obtained as the only tractable product isolated from reaction of 2 and Sb(OEt)₃, while 1 reacted with CdX₂ (X = acac, I) to afford Sn(dmae)₂Cd(acac)₂ ( 4 ) and Sn(dmae)₂CdI₂ ( 5 ). The X‐ray structures of 2, 3 and 4 are reported. Decomposition of 4 under aerosol‐assisted chemical vapour deposition conditions leads to amorphous tin oxide films with no detectable cadmium (i.e. ca < 2% cadmium), rather than a stoichiometric Sn:Cd oxide. Copyright © 2006 John Wiley & Sons, Ltd.     

Structural study on a sulfido-bridged dinuclear organotin(IV) complex with weak Sn ··· Sn bonding

A dinuclear anionic complex, Bu₄N[Me₂SnCl(S)ClSnMe₂Br], has been synthesized in chloroform solution by reacting (Me₂SnS)₃, Me₂SnCl₂, and Bu₄NBr. Attempts to isolate the anionic complex using tetramethylammonium cation were unsuccessful. The anion possesses two five-coordinate tin(IV) units bridged by sulfide and bromide. X-ray diffraction study revealed the possibility of a weak Sn–Sn bond in the complex. Theoretical (DFT) studies have been carried out to analyze the nature of metal–metal interaction in the complex.