Sn Bridges Research Articles

Synthesis and Structure of Tris(trialkylstannyl)‐ and Tris(dialkylhalostannyl)amines; Stabilization of the Sn3N Skeleton by Intramolecular Sn–X–Sn Bridges

AbstractTris(triorganylstannyl)amines (R2R'Sn)3N (1, 2) with substituents R = R' = Me, Bu or R = Me and R' = iPr, tBu are obtained by metathesis from R2R'SnX and NaNH2 in liquid ammonia or by transamination of R3SnNMe2 with NH3. Tris(diorga‐nylhalostannyl)amines (R2XSn)3N (3) are synthesized by stannazane cleavage of (Me3Sn)3N (1) with R2SnX2. Information from multinuclear magnetic resonance spectra ascertain the planarity of the Sn3N skeleton of type 2 and 3, as well as the relationship between the coupling constants 1J(119Sn15N) and 2J(119Sn117Sn) and the Sn–N bond length as determined by the X‐ray structure analysis of 1, 3b and 3r. Compound 3b shows an almost undistorted D3h symmetry with a planar Br3Sn3N skeleton and SnN bond lengths of 1.99 Å, which beside those of 3a are the shortest found so far. According to MNDO approximate and ab initio calculations π interactions between the lone electron pair at the N atom and empty orbitals at the Sn atoms can be excluded. Therefore, the tristan‐nylamines discussed here have a trigonal planar nitrogen center with its lone electron pair in a p‐type orbital. Further characteristic features of the molecular structures of typ 3 compounds are the intramolecular Sn–X–Sn bridges (X = Cl, Br, I) found in the solid state as well as in solution. The molecular geometries of the tristannylamines are supported by MS fragmentation patterns as well as by infrared and Raman spectra.

Structural chemistry of triorganotin fluorides. The crystal structure of tricyclohexyltin fluoride revisited

The crystal structure of tricyclohexyltin fluoride has been redetermined to be polymeric. The compound crystallizes in the trigonal P3c1 space group with a= 11.103(2), c= 8.708(1)A and Z= 2. The Sn–F–Sn bridges are linear and asymmetric with Sn–F distances of 2.051(10) and 2.303(10)A. These distances are rationalised in terms of the structure-correlation method which assumes bond-order conservation and Pauling's relationship between bond length and bond order. The polymeric structure is consistent with the physical properties of Sn(C6H11)3F and variable-temperature Mossbauer spectroscopic data. It is proposed that, for rod-polymeric triorganotin fluorides, the repeat distance can give information about the Sn–F distances.

Synthesis and structure of Ir 4Sn 3(CO) 6{CH(SiMe 3) 2} 5O 3; a heterometallic ‘raft’ with sail hoisted!

Heterometallic raft clusters have been obtained previously for a variety of metals but none for tin and iridium, and more significantly none to date have had metal groups bonded above the raft plane. We report a hexametallic Ir 4Sn 2 raft to which a third tin group is attached by a single short IrSn bond and three IrOSn bridges.

Tris(chlorodimethylstannyl)amine, a Molecule with a Planar Sn3N Skeleton Stabilized by Intramolecular Sn‐Cl‐Sn Bridges

Nearly D3h symmetry, a planar Sn3N framework, almost symmetrical SnClSn bridges and extremely short SnN bonds-these are the features of the skeleton of (ClMe2Sn)3N 1. This unusual structure has been characterized by NMR spectroscopy, quantum chemical calculations, and X-ray structural analysis. No indications of SnN (dp)π bond participation were found.

Preparation and 119 mSn Mössbauer spectral studies of diorganotin(IV) derivatives of isonicotinic acid and isonicotinic acid N-oxide

The following new complexes, (i) R 2Sn( iNic) 2 [1:2], (ii) [R 2Sn iNic] 2O [1:1], (iii) R 2Sn( iNicO) 2 [1:2] and (iv) [R 2Sn iNicO] 2O [1:1] (R = CH 3, nC 4H 9, nC 8H 17, C 6H 5CH 2; iNic = anion of isonicotinic acid, iNicO = anion of isonicotinic acid N-oxide), of isonicotinic acid and isonicotinic acid N-oxide have been prepared with diorganotin(IV) oxides in 1:1 and 2:1 ligand: metal molar ratio. Dibutyl- and dioctyltin(IV) complexes are more soluble than dimethyl- and dibenzyltin(IV) derivatives. IR, 1H NMR and Mössbauer studies show all the 2:1 complexes to have a distorted trans octahedral and the 1:1 complexes a dinuclear trigonal bipyramidal structure with SnOSn bridge. However, the 1:1 complexes of isonicotinic acid N-oxide have present in the same molecule a six and a five coordinate tin(IV) atom, joined by an oxygen atom.

Structural chemistry of organotin carboxylates: XIV. Diorganotin(IV) complexes of monochloroacetyl- lphenylalanine. Crystal structure of [ nBu 2Sn(O 2C(CH 2Ph)C(H)N(H)C(O)CH 2Cl 2) 2

New diorganotin(IV) complexes of the general formulae [R 2Sn(A) 2] and {[R 2Sn(A)] 2O} ( = the anion of monochloroacetyl- l-phenylalanine and R = Me, nPr, nBu and nOct) have been prepared and characterized by 1R and 1H NMR spectroscopy and, in the case of the [ nBu 2Sn(A) 2] compound, by X-ray crystallographic metods. The 1:2 (Sn:ligand) compounds are monomeric, and the Sn atom has a skew trapezoidal planar geometry, whereas the 1:1 compounds are dimeric with SnOSn bridges and possess trigonal bipyramidal Sn atom geometries.

Molecular structure and stereoisomerization of bis(2-dimethylchlorostannylethyl)phenylphosphine oxide

NMR data ( 1H, 13C, 119Sn, 31P) have revealed that in donor-free solvents bis(2-dimethylchlorostannylethyl)phenylphosphine oxide ( 1) has a symmetric bicyclic structure with the two tin atoms intramolecularly coordinated to the PO group. In the presence of pyridine one intramolecular PO → Sn coordination is broken and the fifth coordination site of the corresponding tin atom occupied by a solvent molecule. In both solvents compound 1 undergoes various ligand exchange processes. The crystal structure of compound 1 has been determined by X-ray analysis and refined to a final R value of 0.047. The compound crystallizes in the monoclinic space group P2 1/ c. The structure consists of monocyclic units involving an intramolecular PO → Sn coordination which are associated through intermolecular SnCl … Sn bridges to give infinite zigzag chains parallel to the b-axis. The ligand polyhedra of the two tin atoms exhibit trigonal-bipyramidal geometry, with different deviations from the ideal trigonal-bipyramidal arrangement.

Investigation of transmitting ability of Sn-O binuclear bridge grouping by means of19F NMR

1. On the basis of an investigation of19F-{1H} NMR spectra of a series of 4-fluororphenolates of triaryltins, Ar3SnOC6H4F-4, it has been established that the transmission ability (TA) of the SN-O binuclear bridge grouping differs slightly from that of the Sn bridge atom and the CH2O group. 2. In contrast to the weak proton-donor solvent CHCl3, aprotic polar solvents — either noncoordinating or coordinating — reduce the electron conductivity of Ar3SnOC6H4F-4.

Low-temperature scanning electron microscopy of temperature structures in superconducting bridges

Temperature structures generated in a thin-film superconducting bridge through dissipation of Joule energy can be imaged by low-temperature scanning electron microscopy (LTSEM). Two voltage peaks are obtained at the boundaries of the hotspot, where the temperature profile passes through the critical temperatureTc of the bridge. If the electron beam is modulated at high frequencies the width of the modulated voltage peaks is about twice the dynamic thermal healing length and decreases with increasing modulation frequency. In this way, the spatial resolution of LTSEM can be increased considerably. Experiments performed with an O2-doped Sn bridge up to beam modulation frequencies of 10 MHz confirm these effects. They are in good agreement with all predictions from a theoretical analysis in which the electron beam irradiation is treated as a small thermal perturbation of the sample.

ChemInform Abstract: TIN OXIDE SURFACES. PART 4. INFRARED STUDY OF THE ADSORPTION OF OXYGEN AND CARBON MONOXIDE + OXYGEN MIXTURES ON TIN(IV) OXIDE, AND THE ADSORPTION OF CARBON DIOXIDE ON AMMONIA‐PRETREATED TIN(IV) OXIDE

AbstractDie Adsorption von Sauerstoff an SnO, hat das Auftreten zweier neuer Banden zur Folge, die durch ′SO‐Beimischungen nicht verschoben werden.

X-ray crystallographic, morphological and thermal decomposition studies of 2:1 adducts of diisopropyl methylphosphonate with stannous and stannic halides

X-ray and morphological studies of monomeric, trans-square planar Sn(dimp) 2X 2 ( X  Cl, Br; dimp = diisopropyl methylphosphonate) and trans-octahedral Sn(dimp) 2X 4 ( X = Cl, Br, I) adducts revealed that the crystals of these compounds are triclinic, space group P1. The Sn(II) and Sn(IV) chloride and bromide adducts have four molecules per unit cell, while the SnI 4 adduct has two molecules per unit cell. The two stannous halide adducts are almost isostructural. The X-ray powder patterns of the SnCl 4 and SnBr 4 complexes exhibit some similarities, but that of the SnI 4 adduct is significantly different. Studies of the thermal behavior of the Sn(IV) adducts at 140–210°C, indicated that Sn(dimp) 2 X 4 decomposes in two steps, i.e. (i) Formation of a linear oligomeric species of the type {[( i-C 3H 7O)CH 3POO] 2Sn X 2} n ( n = 4 for X  Cl), involvin Sn(OPO) 2Sn bridges, with simultaneous elimination of propylene and HX. (ii) Decomposition of the preceding oligomeric intermediate to yield highly cross-linked polymeric [(CH 3PO 3) 2Sn] n and isopropyl halide. Poor reproducibility in the amounts of volatile materials evolved from experiment to experiment did not allow the collection of consistent kinetic data for the thermal decomposition of Sn(dimp) 2 X 4. The Sn(dimp) 2 X 2 adducts also decompose at elevated temperatures, yielding a linear, high polymer of the [(CH 3(OH)POO) 2Sn] n type, via formation of the {[( i-C 3H 7O)CH 3POO] 2Sn} n intermediate, which is subsequently attacked by the hydrogen halide present in the system.

Tin oxide surfaces. Part 4.—Infrared study of the adsorption of oxygen and carbon monoxide + oxygen mixtures on tin(IV) oxide, and the adsorption of carbon dioxide on ammonia-pretreated tin(IV) oxide

The transmission infrared technique has been used to study the adsorption of oxygen and carbon monoxide + oxygen mixtures on tin(IV) oxide. Adsorption of oxygen results in the appearance of two weak bands at 1155 and 1020 cm–1 which did not shift using 18O-enriched oxygen. No assignment of the species responsible for these bands was made, but the accompanying broad intense band below 900 cm–1 is associated with surface Sn—O—Sn bridges. Surface carbonate and bicarbonate species are formed slowly when the oxide is exposed to carbon monoxide + oxygen mixtures, essentially independent of the gas mixture composition in the range 10–70 % CO. No bulk reduction of the oxide was observed, in contrast to the behaviour previously observed with carbon monoxide alone. Hydration of the oxide surface prior to treatment with adsorbent severely inhibits the adsorption of carbon dioxide and carbon monoxide + oxygen mixtures. Preadsorbed ammonia has a similar inhibiting effect with carbon dioxide, but leads to the formation of a low stability carbamate salt of the unsubstituted carbamic acid, H2NCO2H.

Organotin carboxylates I. Mösssbauer and infrared study of triphenyltin carboxylates and the novel compounds RSn(O)OCOR∨'

Triphenyltin carboxylates are capable of existing in two forms. The straight-chain compounds are polymeric, with bridging OCO groups and pentacoordinate tin atoms. If the carboxylate chain branches at the α-position the compounds are monomeric and resemble normal esters. The different structures are readily identified from their Mössbauer and infrared spectra. It is shown that at least some of these compounds decompose to yield phenylstannoic carboxylates, which probably exist either as cyclic trimers or linear polymers, with SnOSn bridges and either chelating or ionic carboxyl groups.