SnI4 Research Articles

Polyamorphism in tin tetraiodide

The discovery of a first-order phase transition in fluid phosphorus aroused renewed interest in polyamorphism in liquids with a locally tetrahedral molecular structure. We have performed in situ synchrotron x-ray diffraction measurements on tin tetraiodide, which consists of SnI(4) tetrahedral molecules at ambient pressure, and established that the liquid forms existing above and below 1.5 GPa, where the slope of the melting curve of the solid phase changes abruptly, have different structures. This discovery offers evidence of thermodynamically stable polyamorphism in general compounds as well as in elements. A possible phase diagram that includes the two amorphous states already found is proposed based on the pseudobinary regular solution model. The vertex-to-face orientation between the nearest molecules plays a key role in the transition from the low-pressure to the high-pressure liquid phase.

Equation of state for the low-pressure crystalline phase of tin tetraiodide

Equation of state for the low-pressure crystalline phase of tin tetraiodide

Orientational correlations in molecular liquid SnI4

The total scattering structure factor of liquid tin tetraiodide (SnI(4)) has been interpreted by means of reverse Monte Carlo (RMC) modeling. From the sets of particle coordinates provided by RMC, which are consistent with experimental results within errors, partial radial distribution functions as well as correlation functions characterizing mutual orientations of molecules as a function of distance between molecular centers can be calculated. Interestingly and very much in contrast to liquids of symmetric XCl(4) molecules, the corner-to-face (or "Apollo")-type orientation of neighboring molecules has a significant (about 20%) occurrence in liquid SnI(4). Via comparison with a reference system, obtained by hard sphere Monte Carlo simulation, we demonstrate that intermolecular two-body correlations in liquid SnI(4) are determined largely by excluded volume (steric) effects; that is, intermolecular two-body interactions play only a minor role. On the other hand, as it is manifested in the large difference between the reference and "real" systems in terms of the orientational correlations, higher order interactions are indispensable. This feature can explain the extremely rich phase behavior of SnI(4) at high pressures.

Bis(2-carboethoxyethyl)diiodotin at 120 K

In the structure of the title compound, [Sn(C10H18O4)I2], Sn lies on a crystallographic twofold axis and the mol­ecule therefore has C2 molecular symmetry. As is usual for an ester–tin compound of this kind, the carbonyl O atom of the carboethoxy moiety bonds to Sn, creating a five-membered chelate ring and, due to the molecular symmetry, renders Sn six-coordinate.

Rapid Synthesis of Crystalline Spinel Tin Nitride by a Solid‐State Metathesis Reaction

Spinel tin nitride (Sn3N4) was prepared by high‐pressure solid‐state metathesis reactions. Tin tetraiodide was reacted with lithium nitride and ammonium chloride in a piston–cylinder apparatus at 623 K and 2.5 GPa. Powder X‐ray diffraction combined with Rietveld refinement confirmed the spinel structure, with a lattice constant of a= 9.0144(1) Å. Raman spectroscopy revealed five active vibrational modes at 160, 252, 416, 524, and 622 cm−1, which are consistent with the spinel structure. Mid‐infrared spectroscopy exhibited only a Sn–N stretching mode at 547 cm−1. Transmission electron microscopy was used to reveal particle size and morphology. Electron probe microanalysis was used to verify the elemental composition.

Preparation of both enantiomers of 1-allyl-1,2,3,4-tetrahydro-β-carboline using allyltin reagents and a chiral auxiliary derived from l-proline

β-Carboline, which had an acyl group derived from l-proline at the 9-position, reacted with allyltributyltin and 2,2,2-trichloroethyl chloroformate to afford an 1-allyl-1,2-dihydro-β-carboline derivative in a diastereoselective manner. The chiral acyl group at N-9 was readily eliminated by aqueous alkali to give a corresponding carboxylic acid. The formed 1-allyl-1,2-dihydro-β-carboline was transformed via two reduction steps to 1-allyl-1,2,3,4-tetrahydro-β-carboline in high ee. When the allylation was carried out using tetraallyltin instead of allyltributyltin, the stereoselectivity was reversed, and the antipode of the allyl adduct was obtained in high yield and ee in the presence of tin(IV) tetraiodide. Thus, it was found that both enantiomers of 1-allyl-β-carboline were obtained in good enantioselectivities by the use of the same chiral auxiliary.

Equation of State for Liquid Tin Tetraiodide under Hydrostatic Pressure

Isothermal-isobaric molecular dynamics simulations were carried out for SnI 4 in its liquid state under hydrostatic pressure up to about 5 GPa. The equation of state was obtained from the virial pressure, which was found to be in good agreement with that derived by Boublík regarding a system consisting of hard-convex bodies as a reference fluid. The virial coefficients determined from the equation of state were presented so as to facilitate experimental confirmation.

分子性固体 ヨウ化スズの高圧力下における構造相転移

High-pressure studies of tin tetraiodide SnI4 are reviewed. Recent x-ray diffraction studies have shown that SnI4 undergoes successive phase transitions from an insulator crystalline phase (I; Pa3) to a metallic crystalline phase (II) at 7 GPa, to the amorphous state at about 15 GPa, and to a non-molecular crystalline phase (III; Fm3m) at 61 GPa. The crystal structure of phase III has been determined to be a substitutional disordered structure in which both iodine and tin atoms are randomly located at the fcc sites.

Quantum dots of SnI 4 and its clusters in cyclodextrins

From the reflection spectra of tin tetraiodide (SnI 4) single crystals, the exciton absorption band has been observed at peak energies of 3.14 eV (77 K) and 3.07 eV (room temperature). The exciton binding energy is estimated at 380 meV. The large binding energy suggests that each SnI 4 molecule has a quantum dot-like character. The reflection spectra of the SnI 4 clusters in γ-cyclodextrins were also measured. The first exciton peak of the clusters shift to a higher energy by 0.35 eV (77 K) and 0.40 eV (room temperature) compared with those of the single crystal due to the quantum size effect.

Stannous lodide–HCI in Tetrahydrofuran: A New System for the Reduction of various Nitro Compounds. Mild Conversion of 6-Nitro-Δ 5-Steroids to 6-Keto-steroids

It has been shown that 6-nitro-Δ5-steroids, nitrostyrene and saturated aliphatic nitro compounds in tetrahydrofuran are reduced efficiently with stannous iodide and a catalytic amount of concentrated hydrochloric acid to the corresponding 6-ketosteroids, oximes or hydroxylamine derivatives in good yields, respectively.

Thermodynamics of metalligand bond formation: XXXIV. Lewis acidity of organotin iodides

Thermodynamic data have been obtained by calorimetric titration in benzene solution at 30°C for reactions of N-donor Lewis bases with tin tetraiodide, dimethyl-, diphenyl- and dibenzyl-tin iodides, triphenyl- and tribenzyl-tin iodides, and di- and tri-benzyltin chlorides. The triorganotin iodides form 1:1 adducts of low stability with pyridine or 4-methylpyridine, but do not react with 2,2′-bipyridine or 1,10-phenanthroline. The other compounds form 1:1 adducts with the bidentate bases and both 1:1 and 1:2 adducts with unidentate bases, always of lower stability than adducts with corresponding chlorides. Where addition of successive molecules of base occurs it is found that: K 1 < K 2 and K 1Δ H 1 < K 2Δ H 2.

Electrical conductivity measurements of stannic iodide

Conductivity measurements on insulating molecular materials can be of practical use, but are subject to considerable uncertainty because of variations in carrier density caused by extrinsic factors such as internal purity and perfection, ambient gases and photogeneration of carriers. During the past decade, single crystals of stannic iodide (SnI4) have been the subject of optical and electrical investigations. These studies have advanced the quantitative understanding of photodissociation [ 1 ], photolysis [2] and luminescence [3] of SnI4 materials. The optical absorption edge measures the gap between the conduction and valence bands, in the absence of excitation states and strong impurity absorptions. Whall and Juzova [4] have used the techniques Of transient photoconductivity to investigate the carrier transport in SnI4. Applied research has recently put forward SnI4 as a humidity proof transparent antistatic film coating [5]. SnI4 is an attractive molecular solid having a simple tetrahedral molecule which condenses into crystals of a simple cubic structure and with perfect octahedral habit. The tin and iodine atoms are covalenfly bonded while the intermolecular forces are entirely of van der Waals' type. As far as the authors are aware, electrical conductivity measurements of SnI4 have not been reported in the literature. In this paper, we have reported the behaviour of electrical conduction in the temperature range 30 to l l 0 ° C to understand the mechanism of electrical conduction in SnI4. Single crystals of SnI4 (Fig. i) used in the present investigation were grown by employing the gel-technique [6]. Orange to reddish octahedral SnI4 crystals up to 5 mm in size were obtained. The grown crystals were examined by scanning electron microprobe analysis, X-ray diffraction, density measurements and thermogravimetric analysis, these techniques confirmed that they were SnI4. By chemical analysis the percentage of tin and iodine in SnI4 were estimated as 15% and 83%, respectively. For pellet samples, the laboratory grown crystals were finely ground and the resulting powders, of average particle size 150/am, were compressed in a die under a pressure of 200 kg cm -2, giving a packing fraction of 0.764. The crystal or the pellet, as the case may be, was mounted between the flat platinum electrodes in an ordinary conductivity cell. It was then enclosed in a resistance heated furnace, and the temperature of the sample was monitored using

Dislocation activity in single crystals of stannic iodide

AbstractSingle crystals of stannic iodide (SnI4) have been grown employing the controlled‐reaction between SnCl2 and KI solutions by diffusion process in silica gels. As‐grown (111) surfaces of the crystals have been optically studied. Characteristic growth spirals and hopper growth patterns have been observed on them. By successively etching (111) surfaces in a 0.2 N HCl solution, it is established that the pits indicate the sites of dislocations in the crystals. This is further confirmed by comparing the etch patterns before and after chemically polishing (111) surfaces. The average dislocation in the SnI4 crystals have been determined and found to be 7.3 × 102 cm−2. Observations of polygonisations are described and the implications are discussed.

Nucleation and growth of SnI 4 single crystals in silica gels

A detailed study of the variation in nucleation density and growth of stannic iodide (SnI 4) single crystals as a function of concentration of feed solution, gel aging, gel density and temperature is presented. It has been observed that the low density of gel gives good transparent single crystals and gel aging considerably reduces the number of nucleation sites. It has been found that the nucleation density decreases as the temperature increases. A simple procedure to control nucleation sites in gels has been adopted which has resulted in a dramatic increase in the size of the crystals. The growth of SnI 4 in silica gels under the influence of an externally applied uniform electric field has also been investigated. The implications are discussed.

SEM-studies of tin-iodide whiskers

Optical and scanning electron microscopic observations have been made of tin-iodide whiskers crystals grown by the gel-method. Most of the whiskers have been found to be of two types: (i) hollow and (ii) solid whiskers. The observations indicate that the formation of hollow whiskers is possible with or without the presence of impurities. By using electron micro probe, the overgrowth of tin-tetra iodide crystals on tin-iodide whisker crystals have been identified. A growth mechanism for tin-iodide whiskers have been suggested. The implications are discussed.

Mechanism of the inhibition of oxidation by metal complexes

1. A study has shown that tin tetraiodide repeatedly breaks the oxidation chains in the initiated oxidation of isopropylbenzene at 50–75‡C. Inhibition involves stoichiometric chain rupture through homolytic substitution of the iodine of SnI4 by peroxyl radicals, followed by multiple chain rupture by molecular iodine and alkyl iodides in processes involving alkyl and peroxyl radicals. 2. Stoichiometric coefficients and rate constants have been determined for the reactions of peroxyl and alkyl radicals with SnI4 and molecular iodine, respectively.

Microstructures on {111} faces of stannic iodide single crystals

AbstractSingle crystals of stannic iodide (SnI4) havebeen grown using the controlled reaction between SnCl2 and KI by diffusion process in silica gel medium. Orange to reddish octahedral stannic iodide crystals up to 3–4 mm in size have been grown at room temperature. Optical studies have been made on the various surface structures of {111} faces of the asgrown crystals. On octahedral faces of these crystals, triangular‐shaped hillocks with growth layers in the 〈110〉 directions have been observed. Occasionally, growth spirals on octahedral faces have also been reported. Close loops of growth fronts have been investigated and have been interpreted. It has been suggested that two‐diemensional nucleation, spreading and pilling up of triangular growth layers is mainly responsible for the growth and occasionally the growth is due to screw dislocations. The implications are discussed.

The attachment energy as a habit controlling factor II. Application to anthracene, tin tetraiodide and orthorhombic sulphur

Attachment energies E att have been calculated for F forms of anthracene, SnI 4 and α-sulphur. Assuming the growth rate to be proportional to E att growth habits were obtained. For anthracene this habit is tabular {001} with {20 1 }, {110} and {11 1 };. For SnI 4 the habit is octahedral {111} with small {210} faces. For α-sulphur the growth habit is dipyramidal {111} with {001}, while {113} and {011} have attachment energies that make these faces to lie just outside the edges of the calculated growth form. The equilibrium form shows the faces {111}, {001}, {113}, {011}, {101}, {110} and {100}. Taking into account the approximation involved, the calculated growth habits agree remarkably well with the observed habits.

The Raman spectrum of tin tetraiodide: temperature and pressure measurements and lattice dynamical calculations

Tin tetraiodide was chosen for a temperature and pressure dependent lattice dynamical study because of its pronounced anharmonic properties. The variation of the Raman spectrum with temperature from 100K to 298K has been measured using a single-crystal specimen. The temperature dependence of the mode frequencies and linewidths are given together with symmetry assignments. Further measurements were made at room temperature using a powdered sample under pressure, showing considerable variation in internal as well as external modes. Isochoric and isobaric temperature shifts, relative pressure shifts and Gruneisen parameters are obtained from these data. The group theory for this system is presented. The authors' analysis was confirmed by extensive lattice dynamical calculations, first using a model in which the molecules were assumed to be rigid units, and then using a model which gave the internal modes as well as the lattice modes. The pressure variation was also calculated using both models.

Tungsten-Halogen Lamp Dosed with Tin Tetraiodide

The authors discuss the development of an iodine cycle halogen lamp of higher intrinsic luminous efficiency. It can be operated in any position. It has the reliability of the long life iodine lamp and has most of the desired characteristics of the bromine cycle lamp. The performance of the iodine cycle lamp has, therefore, been improved so that many similar lamp types need not be considered for a changeover to the bromine cycle.