Sn Interactions Research Articles

Nanocrystalline CoSn 2-carbon composite electrode prepared by using sonochemistry

A sonochemical method has been used to prepare negative electrode materials containing intermetallic nanoparticles and polyacrylonitrile (PAN). The ultrasound irradiation is applied to achieve small particle size. After annealing at 490 °C under Ar-flow, the polymer PAN is partially carbonized and the metallic nanoparticles are surrounded by a carbonaceous matrix. The main metallic phase is CoSn 2. The carbonaceous coating and the surface oxides have been explored by using XPS. The resulting CoSn 2-carbonaceous phase electrode (CoSn 2@C) shows improved electrochemical behavior (ca. 450 mAh/g after 50 cycles) in comparison with previous reports on pure crystalline CoSn 2. The reaction between CoSn 2@C and Li has been studied by using XRD and 119Sn Mössbauer spectroscopy. The formation of large grains of crystalline Li x Sn phases after the first discharge is discarded. The small particle size which is achieved by using ultrasonication and the carbonaceous matrix contribute to maintain the Co–Sn interactions during the electrochemical cycling. The aggregation of the nanosized metallic particles upon electrochemical cycling can be suppressed by the carbonaceous matrix (pyrolytic PAN).

Use of bis-aminoalcohol benzoquinones and dihydroxybenzoquinones in the formation of mono and polymeric structures of diorganotin(IV) derivatives

Reaction of three hexadentate ligands ( L1– L3) derived from 1,4-benzoquinone bis(aminoalcohols) with diorganotin oxides (R 2Sn-O) n (with R = Me, nBu, Ph) in 1:2 stoichiometric proportions lead to the formation of dinuclear tin compounds of the composition [(R 2Sn) 2(L)], wherein the five-coordinate metal centers are embedded in distorted trigonal-bipyramidal polyhedra. X-ray diffraction analysis revealed that diorganotin complexes carrying n-butyl groups tend to associate further through intermolecular O⋯Sn interactions to give 1D polymeric chains, while diphenyltin analogues tend to be monomeric. On the other hand, using 2,5-dihydroxy-3,6-dichloro-1,4-benzoquinone as ligand ( L4) in 1:1 reactions with the diorganotin oxide derivatives, 1D polymeric complexes of the composition [R 2Sn(L4)(DMSO)] n with seven-coordinate metal centers in distorted pentagonal-bipyramidal coordination polyhedra were obtained. In this case, the presence of different substituents attached to the tin atoms (Me, nBu, Ph) had no influence on the molecular composition of the products, but on the conformation of the polymeric chain, which was either planar (R = Me), slightly distorted from planarity (R = nBu) or ondulated (R = Ph).

Influence of preparation method and boron addition on the metal function properties of RuSn catalysts for selective carbonyl hydrogenation

AbstractBACKGROUND: Improvements in the selective hydrogenation of unsaturated fatty acid methyl esters in order to obtain unsaturated fatty alcohols have been attempted through the preparation and modification of supported group VIII metallic catalysts. Suitable catalysts appear to be those based on supported Ru modified by Sn. The influence of preparation and activation methods on the structural and electronic properties of the metallic phase and the effect of modifications to these properties on the catalytic performance of RuSn/Al2O3 catalysts was studied regarding selective hydrogenation of carbonyl groups.RESULTS: Preparation methods have a marked influence on the electronic state of Ru and its interaction with Sn. Temperature‐programmed reduction (TPR), Fourier transform infrared spectroscopy of chemisorbed CO (FTIR‐CO) and X‐ray photoelectron spectroscopy (XPS) results clearly show that the incorporation of sodium borohydride in the preparation leads to a greater RuSn interaction when compared with catalysts prepared by co‐impregnation without B. The activation of catalysts without B (either by direct reduction or calcinations‐reduction) does not produce a strong RuSn interaction. B‐containing catalysts exhibit higher hydrogenolytic and lower dehydrogenating activities. Selectivity towards oleyl alcohol formation was 37% for this catalyst, while catalysts without B were not suitable for obtaining fatty alcohols.CONCLUSION: The degree of interaction between Ru and Sn strongly depends on catalyst preparation and activation method where strong interaction promotes selectivity with respect to oleyl alcohol formation. On the contrary, catalysts with a weak RuSn interaction do not show significant selectivity for the unsaturated alcohol. Copyright © 2010 Society of Chemical Industry

Organotin-Substituted [13]-Crown-4 Ethers: Ditopic Receptors for Lithium and Cesium Halides

The synthesis of the organotin- and the bis(organostannyl)methane-substituted crown ethers Ph(3−n)XnSnCH2-[13]-crown-4 (1, n = 0; 2, n = 1, X = I; 3, n = 1, X = Cl; 4, n = 1, X = F; 5, n = 2, X = I; 6, n = 3, X = I; 8, n = 3, X = Cl; 9, n = 2, X = Cl) and Ph(3−n)XnSnCH2Sn(X)nPh(2−n)CH2-[13]-crown-4 (10, n = 0; 11, n = 1, X = I; 12, n = 2, X = I; 13, n = 1, X = F; 14, n = 2, X = Cl) as well as of the ditopic complexes 8·LiCl·H2O and Ph2(SCN)SnCH2-[13]-crown-4·LiSCN (15·LiSCN) are reported. These compounds were characterized by elemental analyses, by 1H, 13C, 19F, and 119Sn NMR spectroscopy, electrospray mass spectrometry, and in the case of 2 and 4 also by 119Sn MAS NMR spectroscopy. Single-crystal X-ray diffraction analyses reveal distorted tetrahedral configurations for the tin atoms in compounds 1, 11 (Sn2), and 12 (Sn2), whereas intramolecular O→Sn interactions (Sn−O = 2.416(2) (6) to 2.471(3) (11, Sn1) A) characterize the molecular structures of compounds 2, 6, 9, and 11 (Sn1), in which the tin atoms ...

Dative P→Sn interactions in ortho-phenylene phosphine-stannanes

Abstract Monophosphine and diphosphine-stannane compounds 1 and 2 are shown spectroscopically, structurally and theoretically to present rare intramolecular P→Sn interactions.

Design of a 120 mm Bore 15 T Quadrupole for the LHC Upgrade Phase II

Future upgrades to machines like the Large Hadron Collider (LHC) at CERN will push accelerator magnets beyond 10 T forcing the replacement of NbTi superconductors with advanced superconductors such as Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn. In support of the LHC Phase-II upgrade, the US LHC Accelerator Research Program (LARP) is developing a large bore (120 mm) Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn Interaction Region (IR) quadrupole (HQ) capable of reaching 15 T at its conductor limit and gradients of 199 T/m at 4.4 K and 219 T/m at 1.9 K. The 1 m long, two-layer magnet, addresses coil alignment and accelerator quality features while exploring the magnet performance limits in terms of gradient, stress and structure. This paper summarizes and reports on the design, mechanical structure, coil windings, reaction and impregnation processes.

Effect of the Synthesis Method of MgAl2O4and of Sn and Pb Addition to Platinum Catalysts on the Behavior inn-Butane Dehydrogenation

The MgAl2O4 spinels, synthesized by using two different methods (ceramic and coprecipitation), show very low acidity and good dispersion capacity of the metallic phase, these properties being suitable for the use of these materials as supports. However, MgAl2O4cer displays higher strong acidity than MgAl2O4cop which seems to influence the metal−support interaction, since Pt/MgAl2O4cer catalyst shows higher metallic dispersion, lower metal particle sizes, and better catalytic behavior than the Pt/MgAl2O4cop one. The Sn addition to Pt/MgAl2O4 improves the performance in the n-butane dehydrogenation process, increasing the activity, stability, and selectivity to butenes. This behavior is due to the presence of important Pt−Sn interactions, mainly in bimetallic catalysts supported on MgAl2O4cer. On the other hand, the Pb addition to monometallic catalysts does not enhance the catalytic performance in dehydrogenation. This behavior is in agreement with the characterization results of metallic phase that indicate important blocking effects in PtPb/MgAl2O4cer catalysts, and segregation effects in PtPb/MgAl2O4cop. In conclusion, the ceramic method of MgAl2O4 preparation provides the best support for PtSn catalysts in n-butane dehydrogenation reaction.

Electronic Structures and Transport Properties of Single-Filled CoSb3

Band structure and density of states (DOS) of CoSb3 single-filled by seven kinds of atoms (R0.125Co4Sb12) are calculated by the density functional method. The results for the electronic structures in turn determine the electrical transport and thermal performance. It is found that the band structure of R0.125Co4Sb12 shows no significant changes compared with that of CoSb3, and the results indicate that void filling with a small quantity of R atoms does not change the bond formation in CoSb3. However, the partial DOS reveals that there could be interaction of Sn, Tl, In, and Yb atoms with CoSb3. The results for the electrical transport properties and thermal properties show that Sn, Tl, and In atoms increase the Seebeck coefficient and La, Eu, and Yb atoms are helpful for increasing the electron concentration and decreasing the thermal conductivity further. According to our calculations and Yang’s principle, double-filled CoSb3 with atomic combinations of (In, Ca), (In, Ba), (Sn, Eu), and (Sn, La) may exhibit good thermoelectric performance.

Tetrakis(μ2-4-aminobenzoato)di-μ3-oxido-tetrakis[dibutyltin(IV)

The molecule of the title compound, [Sn(4)(C(4)H(9))(8)(C(7)H(6)NO(2))(4)O(2)], lies about an inversion centre and is a tetranuclear bis(tetrabutyldicarboxylatodistannoxane) complex containing a planar Sn(4)O(2) core in which two mu(3)-oxide O atoms connect an Sn(2)O(2) ring to two exocyclic Sn atoms. Each Sn atom has a highly distorted octahedral coordination. In the molecule, the carboxylate groups of two aminobenzoate ligands bridge the central and exocyclic Sn atoms, while two further aminobenzoate ligands have highly asymmetric bidentate chelation to the exocyclic Sn atoms plus long O...Sn interactions with the central Sn atoms. Each Sn atom is also coordinated by two pendant n-butyl ligands, which extend roughly perpendicular to the plane of the Sn(4)O(10) core. Only one of the four unique hydrogen-bond donor sites is involved in a classic N-H...O hydrogen bond, and the resulting supramolecular hydrogen-bonded structure is an extended two-dimensional network which lies parallel to the (100) plane and consists of a checkerboard pattern of four-connected molecular cores acting as nodes. The amine groups not involved in the hydrogen-bonding interactions have significant N-H...pi interactions with neighbouring aminobenzene rings.

Gold–Silane and Gold–Stannane Complexes: Saturated Molecules as σ‐Acceptor Ligands

Gold gets a grip: Spectroscopic, structural, and computational results provide evidence for unprecedented Au→Si and Au→Sn interactions in gold(I) complexes derived from diphosphino-substituted silane and stannane ligands (see scheme).

Organotin catalysts grafted onto cross‐linked polystyrene supports through polar spacers

AbstractThe present study investigates the suitability of a HypoGel support bearing oligomeric poly(ethylene glycol) (PEG) chains to act as an insoluble carrier for grafted organotin catalysts. Through the introduction of polar spacers, an improved swelling and site accessibility in the polar media typically involved in transesterification reactions are targeted. Advanced structural investigation shows that quantitative conversion into the targeted HypoGel‐supported organotin trichloride is hampered by the existence of intra‐ and/or intermolecular donor‐acceptor O→Sn interactions caused by the presence of donor moieties in the PEG‐linker. Support is provided to the proposal that the latter interactions are at the origin of the moderate catalytic performance displayed by these HypoGel‐supported catalysts, achieving only 41% conversion after 2 hours in the transesterification of ethyl acetate and n‐octanol. In contrast with similar organotin catalysts supported by an alkyl spacer, the HypoGel‐supported materials appear to be poorly recyclable and display poor leaching resistance. Copyright © 2009 John Wiley &amp; Sons, Ltd.

Chiral organotin complexes stabilized by C,N-chelating oxazolinyl-o-carboranes

Abstract A series of chiral organotin halides containing 2-(4-R)-oxazolinyl-o-carboranes (R = i-propyl 1, t-butyl 2; CabOxa) was prepared from o-carborane with a chiral oxazoline auxiliary. X-ray structural analysis of the representative chiral organotin halide, [2-(4-i-propyl)-oxazolinyl-o-carboranyl]SnMe2Br (4), revealed the formation of a stable penta-coordinated tin center due to a N → Sn interaction. Similar O → Sn assisted intramolecular penta-coordinated tin complexes (9 and 10) were prepared from methoxy-o-carborane ligands, MeOCH(Z)-o-carborane (Z = H 7, Ph 8; CabOMe), respectively, and a rigid o-carboranyl backbone provided the basic skeleton for the facile formation of organotin complexes.

Influence of tin addition by redox reaction in different media on the catalytic properties of Pt-Re/Al 2O 3 naphtha reforming catalysts

The influence of Sn addition by catalytic reduction method on the Pt-Re/Al 2O 3 properties for the n-C 7 reforming reaction was studied. The Sn addition was performed in different media (HCl and H 2O). It was found that trimetallic Pt-Re-Sn/Al 2O 3-Cl catalysts prepared in H 2O or HCl medium present a good interaction between Sn and the catalytically active species (Pt-Re). This strong interaction of Sn with the active phase correlates with the lower hydrogenolytic and dehydrogenating activity of the trimetallic catalysts. Total acidity and Brønsted acidity decrease with the addition of Sn. The catalysts prepared in HCl have both higher Brønsted and total acidity in comparison to those prepared in H 2O. In the case of catalysts prepared in HCl medium, the production of C 2–C 4 gases in the n-C 7 reforming reaction also decreases upon Sn addition confirming that the cracking activity decreases when the acidity is decreased. In both trimetallic catalysts series a decrease in the toluene yield can be seen at high Sn contents. The production of toluene depends on the activity in dehydrocyclization reaction. Dehydrocyclization requires sites of lower acid strength than those needed for cracking. The addition of small amounts of Sn (≤0.2 wt%) would enable the step of sulfidation of Pt-Re/Al 2O 3 catalysts to be spared.

Effect of tin on the corrosion behavior of low-alloy steel in an acid chloride solution

This study examined the effect of Sn addition ranging from 0 to 0.1 wt.% on the electrochemical properties of low-alloy steel using electrochemical techniques in an acid chloride solution and surface analysis techniques. The potentiodynamic test showed the active corrosion behavior of all specimens and the corrosion rate decreased with increasing Sn addition. EIS showed that the Sn-containing steels had higher rust layer resistance. These results confirmed that the interaction of Sn with Cu and Sb improves the corrosion resistance of low-alloy steel due to the formation of the continuous tin oxide, copper oxide and antimony oxide layer.

DFT Study on Nano Structures of Sn/CNT Complex for Potential Li-Ion Battery Application

From first principles calculations, we investigate the adsorption of a number of Sn structures (a single atom, a cluster, and an atomic wire) on the inner and outer surfaces of single-walled carbon nanotubes (CNTs); with an interest in the potential applications of these systems to Li-ion batteries. We find that Sn clusters have a much weaker interaction with the CNTs than single Sn atoms and that the interaction of Sn with the outer surface of the CNT is about 2−3 times greater than with the inner surface. The Sn atomic wire is stable inside zigzag (n, 0) CNTs, when n is greater than 10; moreover, we find that the adsorption energy reaches a maximum (−0.19 eV) at n = 14 or 15. Our simulation results explain well experimental observations and suggest that CNT-encapsulated Sn is a potential anode material for Li-ion batteries, with the ability to withstand the huge volume changes that occur upon Sn alloying with Li.

Sialoadhesin-Positive Macrophages Bind Regulatory T Cells, Negatively Controlling Their Expansion and Autoimmune Disease Progression

An important regulatory suppressive function in autoimmune and other inflammatory processes has been ascribed to CD4(+)Foxp3(+) regulatory T cells (Tregs), which requires direct cell-cell communication between Tregs, effector T cells, and APCs. However, the molecular basis for these interactions has not yet been clarified. We show here that sialoadhesin (Sn), the prototype of the siglec family of sialic acid-binding transmembrane proteins, expressed by resident and activated tissue-infiltrating macrophages, directly binds to Tregs, negatively regulating their expansion in an animal model of multiple sclerosis (MS), experimental autoimmune encephalomyelitis (EAE). In this model, macrophages infiltrate the CNS exhibiting tissue-destructing and demyelinating activity, leading to MS-like symptoms. We show here that severity of EAE symptoms is reduced in Sn knockout (KO) mice compared with wild-type littermates due to an up-regulation of CD4(+)Foxp3(+) Treg lymphocytes. Through the use of a Sn fusion protein, Tregs were shown to express substantial amounts of Sn ligand on their cell surface, and direct interaction of Sn(+) macrophages with Tregs specifically inhibited Treg but not effector T lymphocyte proliferation. Conversely, blocking of Sn on macrophages by Sn-specific Abs resulted in elevated proliferation of Tregs. Data indicate that Sn(+) macrophages regulate Treg homeostasis which subsequently influences EAE progression. We propose a new direct cell-cell interaction-based mechanism regulating the expansion of the Tregs during the immune response, representing a "dialogue" between Sn(+) macrophages and Sn-accessible sialic acid residues on Treg lymphocytes.

Bis(2,6-diamino-3,5-dibromopyridinium) hexabromidostannate(IV)

The asymmetric unit of the title compound, (C5H6Br2N3)2[SnBr6], contains one cation and one half-anion in which the Sn atom is located on a crystallographic centre of inversion and is in a quasi-octa­hedral geometry. The crystal structure is assembled via hydrogen-bonding inter­actions of two kinds, N(pyridine/amine)—H⋯Br—Sn, along with C—Br⋯Br—Sn interactions [3.4925 (19) Å]. The cations are involved in π–π stacking, which adds an extra supra­molecularity as it presents a strong case of offset-face-to-face motifs [centroid–centroid distance = 3.577 (3) Å]. The inter­molecular hydrogen bonds, short Br⋯Br inter­actions and π–π stacking result in the formation of a three-dimensional supra­molecular architecture.

LSn(OCH2CH2)2NR (L = lone pair, W(CO)5; R = Me, t‐Bu). The Molecular Structures of 5‐Aza‐2,8‐dioxa‐1‐stannabicyclo[3.3.0]1.5octanes and Their Tungstenpentacarbonyl Complexes

AbstractSingle crystal X‐ray diffraction analyses of LSn(OCH2CH2)2NR [1, R = Me, L = lone pair; 2, R = Me, L = W(CO)5; 3, R = t‐Bu, L = W(CO)5] reveal these compounds to be dimeric and cis‐configurated. The dimerization is realized by intramolecular O→Sn interactions to give four‐membered Sn2O2‐rings. In addition, there are intramolecular N→Sn interactions ranging in between 2.356(5) (2) and 2.549(4) Å (3).

Syntheses and characterization of triorganotin(IV) complexes of Schiff base derive from 4-amino-5-phenyl-4H-1,2,4-triazole-3-thiol and 5-amino-1,3,4-thiadiazole-2-thiol with p-phthalaldehyde

Eight triorganotin complexes of the types [(R 3Sn) 2(C 24H 16N 8S 2)].Y (R = Ph, Y = 0 ( 1); R = PhCH 2, Y = 2CH 3OH ( 2); R = n-Bu, Y = 0 ( 3)), [(R 3Sn) 2(C 24H 16N 8S 2)] n (R = Me ( 4)), [(R 3Sn) 2(C 12H 6N 6S 4)] · Y (R = Ph, Y = CH 2Cl 2 ( 5); R = PhCH 2, Y = 0 ( 6)) and [(R 3Sn) 2(C 12H 6N 6S 4)] (R = Bu ( 7), R = Me ( 8)) have been obtained by H 2L 1 (H 2L 1 derived from 4-amino-5-phenyl-4H-1,2,4-triazole-3-thiol) and H 2L 2 (H 2L 2 derived from 5-amino-1,3,4-thiadiazole-2-thiol) with triorganotin chloride in the presence of sodium ethoxide. All the complexes were characterized by elemental, IR and NMR spectra analyses, except for complexes 1, 3, 6 and 8, other complexes were also characterized by X-ray diffraction analyses, which reveal that complexes 2 and 5 are dinuclear structures, complex 4 has a 2D network structure and complex 7 forms a macrocyclic structure linked by intermolecular N → Sn interactions.

Solvothermal Synthesis and Crystal Structure of a Novel 3D Triorganotin Polymer Containing Polyfunctional Ligand 5-mercapto-1(H)-tetrazoleacetic acid

A novel 3D tri-n-butyltin complex [(n-Bu3Sn)2(C2H2N4SCO2)]n (1) has been solvothermally synthesized and structurally characterized by elemental analysis, FT-IR, NMR (1H, 13C, and 119Sn) spectra and X-ray crystallography. X-ray data of complex 1 reveals that it is a 3D tri-n-butyltin coordination polymer with a metal-organic framework (MOF) structure , significant N → Sn interactions plays an important role in the construction of this structure.