- Magnetic isotope effect in the photolysis of organotin compounds
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Photolysis of organotin molecules RSnMe3 is shown to be a spin selective radical reaction accompanied by fractionation of magnetic, 117,119Sn, and nonmagnetic, 118,120Sn, isotopes between starting reagents and products. A primary photolysis process is a homolytic cleavage of the C-Sn bond and generation of a triplet radical pair as a spin-selective nanoreactor. Nuclear spin dependent triplet-singlet conversion of the pair results in the tin isotope fractionation. Experimentally detected isotope distribution unambiguously demonstrates that the classical, mass-dependent isotope effect is negligible in comparison with magnetic, spin-dependent isotope effect.
- Buchachenko, Anatoly L.,Ivanov, Vladimir L.,Roznyatovsky, Vitaly A.,Ustynyuk, Yuri A.
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- Reaction of α-(trialkylstannyl)acetylenes with metallic sodium
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α-Trialkylstannylacetylenes react under mild conditions with metallic sodium at the Sn-C(sp) bond to give hexaalkyldistannanes and sodium acetylalkynides in ca. 65 - 85percent yields. - Key words: α-(trialkylstannyl)acetylenes, reaction with sodium; hexaa
- Komarov, N. V.,Andreev, A. A.,Shein, O. G.
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- Chemically induced magnetic isotope effect on the tin nuclei during the photolysis of (1-fluorenyl)trimethyltin
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A magnetic isotope effect on the 117Sn and 119Sn nuclei, accompanied by the fractionation of magnetic and nonmagnetic tin isotopes, was observed during the photolysis of (9-fluorenyl)trimethyltin. The magnetic and nonmagnetic isotopes were accumulated, respectively, in the initial compound and a photolysis product (hexamethyldistannane). Nauka/Interperiodica 2006.
- Buchachenko,Roznyatovskii,Ivanov,Ustynyuk
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- The palladium-catalysed addition of hexamethylditin to 1,3-dienes
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The addition of the tin-tin bond of hexamethylditin to some 1,3-dienes occurs readily in the presence of the catalyst system palladiumbis(dibenzylideneacetone)/triethyl phosphite.
- Mitchell, T.N.,Kowall, B.,Killing, H.,Nettelbeck, C.
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- A simple synthesis of hexamethyldistannane from bis(trimethylstannyl)sulphide
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A new and cheap synthesis of hexamethyldistannane has been devised starting from bis(trimethylstannyl)sulphide, itself prepared a new method.
- Capozzi, Giuseppe,Menichetti, Stefano,Ricci, Alfredo,Taddei, Maurizio
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- Microsolvation, aggregation, and pseudomonomolecular, ionic sp 2-stereoinversion mechanism of two exocyclic β,β-di-tert- alkyl-α-arylvinyllithiums This article is dedicated to Professor Paul Knochel in recognition of his kind support.
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A THF-solvated, crystalline, exocyclic alkenyllithium, (tert-alkyl) 2CC(Li)-Ph, was synthesized and shown to be a disolvated dimer in the solid state and in toluene as the solvent; increasing amounts of the monomeric species emerged on cooling the toluene solution. In THF as the solvent, only the trisolvated monomer was present and identified as a contact ion pair (CIP) through its scalar 13C,6Li NMR coupling. This ground-state needs only one further THF ligand as a catalyst for breaking the C-Li bond with formation of a tetrasolvated, solvent-separated ion pair (SSIP) on the way to the transition state of cis/trans sp2-stereoinversion. The ensuing pseudomonomolecular, ionic mechanism is confirmed by low pseudoactivation parameters: enthalpy ΔHψ? = 6.9(3) kcal mol-1; entropy ΔSψ? = -23.3(9) cal mol-1 K-1. Similar parameters were found with 2,6-dimethylphenyl in place of Ph.
- Knorr, Rudolf,Hennig, Karsten-Olaf,B?hrer, Petra,Schubert, Bernhard
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p. 125 - 135
(2014/07/08)
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- Reactions of a Zn(i) complex with group 14 azides-formation of zinc azide and zinc hexazene complexes
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Two zinc hexazene complexes L2Zn2(μ-1,6-R 2-N6) (L = HC[C(Me)N(2,4,6-Me3C 6H2)]2; R = Ph (3), Dipp = 2,6-i-Pr 2C6H3 (4)), were synthesized by reaction of the Zn(i) complex L2Zn2 (1) with phenyl azide and 2,6-diisopropylphenyl azide, respectively. 3 represents the second structurally characterized transition metal hexazene complex. In contrast, reactions of 1 with Me3MN3 (M = Si, Sn) yielded the azido complex [LZn(μ-N3)]2 (2) and Me3M-MMe3.
- Gondzik,Schulz,Blaeser,Woelper,Haack,Jansen
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supporting information
p. 927 - 929
(2014/01/06)
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- Low-coordinate cobalt fluoride complexes: Synthesis, reactions, and production from C-F activation reactions
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A cobalt(II) fluoride complex, [LtBuCo(μ-F)]2 [LtBu = 2,2,6,6-tetramethyl-3,5-bis(2,6-diisopropylphenylimido)hept- 4-yl], was synthesized from LtBuCo using Me3SnF via homolytic cleavage of the Sn-F bond. LtBuCo also performed the overall binuclear oxidative addition of fluorinated arenes to give [L tBuCo(μ-F)]2 and a cobalt(II) aryl complex of the corresponding fluorobenzene substrate in a 1:2 molar ratio. The C-F activation reaction has a first-order rate dependence on both cobalt and fluorobenzene concentrations. The rate is increased by meta-fluoride substituents, and slowed by ortho-fluoride substituents, suggesting electronic and steric influences on the transition state, respectively. The data are most consistent with a mechanism beginning with rate-limiting oxidative addition of the aryl fluoride to cobalt(I), followed by rapid reduction of the cobalt(III) aryl fluoride intermediate by a second molecule of LtBuCo. [LtBuCo(μ- F)]2 also reacts with Et3SiH to give the hydride complex [LtBuCo(μ-H)]2. This hydride complex has low reactivity toward alkenes and N2, in contrast to an earlier report.
- Dugan, Thomas R.,Goldberg, Jonathan M.,Brennessel, William W.,Holland, Patrick L.
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p. 1349 - 1360
(2012/04/10)
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- Synthesis of 1-stannacyclopent-3-enes and their pyrolysis to stannylenes
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1,1-Diorgano-1-stannacyclopent-3-enes have been synthesized by condensation in THF of magnesium complexes of 1,3-dienes and dichlorodiorganostannanes. 1,1-Dimethyl-, 1,1-di-n-butyl-, 1,1-di-tert-butyl-, and 1,1-diphenyl-1- stannacyclopent-3-enes and 1,1,3
- Zhou, Dong,Reiche, Clemens,Nag, Mrinmoy,Soderquist, John A.,Gaspar, Petet P.
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p. 2595 - 2608
(2009/10/01)
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- Stereoselective radical tandem cyclohydrostannation of optically active di-unsaturated esters of TADDOL
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This paper reports the results obtained in a study on the radical addition of triorganotin hydrides, R3SnH (R = Me, n-Bu, Ph; Neophyl), to four TADDOL unsaturated diesters. It was found that diese reactions lead in high yields to products of cyclohydrostannation. It was also found that whereas the addition of these hydrides to TADDOL diacrylate and TADDOL dimethacrylate leads to the expected mixtures of two and four cycloundecane diastereoisomers, respectively, the addition of triphenyltin hydride to TADDOL disubstituted acrylates yields only four out of the 16 possible stereoisomers. The observed high stereoselectivity is consistent with the radical tandem cyclohydrostannation mechanism proposed. Only in the case of the hydrostannation of TADDOL diacrylate with trimethyl- and triphenyltin hydrides could the diastereoisomers obtained in higher proportion (5a and 8a) be isolated in pure form. The subsequent reduction (lithium aluminum hydride) of macrolides 5a and 8a afforded the corresponding optically active diols 26 and 27 in high yield. Full 1H, 13C, and 119Sn NMR data are given.
- Gerbino, Dario C.,Koll, Liliana C.,Mandolesi, Sandra D.,Podesta, Julio C.
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p. 660 - 665
(2009/01/30)
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- Use of neodymium diiodide in the synthesis of organosilicon, -germanium and -tin compounds
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The reactivity of neodymium diiodide, NdI2 (1), towards organosilicon, -germanium and -tin halides has been investigated. Compound 1 readily reacts with Me3SiCl in DME to give trimethylsilane (6 %), hexamethyldisilane (4 %) and (Mes
- Balashova, Tatyana V.,Kusyaev, Dmitry M.,Kulikova, Tatyana I.,Kuznetsova, Olga N.,Edelmann, Frank T.,Giessmann, Stephan,Blaurock, Steffen,Bochkarev, Mikhail N.
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p. 256 - 260
(2008/10/09)
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- Organotin compounds as reagents for the synthesis of lanthanoid complexes by redox transmetallation reactions
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Redox transmetallation reactions between trimethyltin compounds, SnMe 3L [L = 3,5-diphenylpyrazolate (Ph2pz), 2,6-di-tert-butyl-4-methylphenolate (OAr), or C6F5] and lanthanoid metals have yielded [Ln(Ph2/
- Beaini, Samar,Deacon, Glen B.,Hilder, Matthias,Junk, Peter C.,Turner, David R.
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p. 3434 - 3441
(2007/10/03)
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- Direct detection of dimethylstannylene and tetramethyldistannene in solution and the gas phase by laser flash photolysis of 1,1- dimethylstannacyclopent-3-enes
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The photochemistry of 1,1-dimethyl- and 1,1,3,4-tetramethylstannacyclopent- 3-ene (4a and 4b, respectively) has been studied in the gas phase and in hexane solution by steady-state and 193-nm laser flash photolysis methods. Photolysis of the two compounds results in the formation of 1,3-butadiene (from 4a) and 2,3-dimethyl-1,3-butadiene (from 4b) as the major products, suggesting that cycloreversion to yield dimethylstannylene (SnMe2) is the main photodecomposition pathway of these molecules. Indeed, the stannylene has been trapped as the Sn-H insertion product upon photolysis of 4a in hexane containing trimethylstannane. Flash photolysis of 4a in the gas phase affords a transient absorbing in the 450-520-nm range that is assigned to SnMe2 by comparison of its spectrum and reactivity to those previously reported from other precursors. Flash photolysis of 4b in hexane solution affords results consistent with the initial formation of SnMe2 (λ max ≈ 500 nm), which decays over ~10 μs to form tetramethyldistannene (5b; λmax ≈ 470 nm). The distannene decays over the next ca. 50 μs to form at least two other longer-lived species, which are assigned to higher SnMe2 oligomers. Time-dependent DFT calculations support the spectral assignments for SnMe2 and Sn2Me4, and calculations examining the variation in bond dissociation energy with substituent (H, Me, and Ph) in disilenes, digermenes, and distannenes rule out the possibility that dimerization of SnMe2 proceeds reversibly. Addition of methanol leads to reversible reaction with SnMe2 to form a transient absorbing at λmax ≈ 360 nm, which is assigned to the Lewis acid-base complex between SnMe 2 and the alcohol.
- Becerra, Rosa,Gaspar, Peter P.,Harrington, Cameron R.,Leigh, William J.,Vargas-Baca, Ignacio,Walsh, Robin,Zhou, Dong
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p. 17469 - 17478
(2007/10/03)
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- Palladium pincer complex catalyzed stannyl and silyl transfer to propargylic substrates: Synthetic scope and mechanism
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Pincer complex catalyzed substitution of various propargylic substrates could be achieved using tin- and silicon-based dimetallic reagents to obtain propargyl- and allenylstannanes and silanes. These reactions involving chloride, mesylate, and epoxide substrates could be carried out under mild conditions, and therefore many functionalities (such as COOEt, OR, OH, NR, and NAc) are tolerated. It was shown that pincer catalysts with electron-supplying ligands, such as NCN, SCS, and SeCSe complexes, display the highest catalytic activity. The catalytic substitution of secondary propargyl chlorides and primary propargyl chlorides with electron-withdrawing substituents proceeds with high regioselectivity providing the allenyl product. Opening of the propargyl epoxides takes place with an excellent stereo- and regioselectivity to give stereodefined allenylstannanes. Silylstannanes as dimetallic reagents undergo an exclusive silyl transfer to the propargylic substrate affording allenylsilanes with high regioselectivity. According to our mechanistic studies, the key intermediate of the reaction is an organostannane (or silane)-coordinated pincer complex, which is formed from the dimetallic reagent and the corresponding pincer complex catalyst. DFT modeling studies have shown that the trimethylstannyl functionality is transferred to the propargylic substrate in a single reaction step with high allenyl selectivity. Inspection of the TS structures reveals that the trimethylstannyl group transfer is initiated by the attack of the palladium-tin σ-bond electrons on the propargylic substrate. This is a novel mechanism in palladium chemistry, which is based on the unique topology of the pincer complex catalysts.
- Kjellgren, Johan,Sunden, Henrik,Szabo, Kalman J.
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p. 1787 - 1796
(2007/10/03)
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- New method of synthesis of 1,1-bis(trialkylsilyl)- and bis(trialkylgermyl) germacyclopenta-2,4-dienes
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The reactions of 1,1-dichloro-2,3,4,5-tetraphenyl-1-germacyclopenta-2,4- diene (1), magnesium, and R3ECl (E = Si, Ge) under mild conditions (20°C, THF) gave 1,1-bis(trimethylsilyl)-2,3,4,5-tetraphenyl-1- germacyclopenta-2,-4-diene (2a) and 1,1-
- Lalov,Nosov,Egorov,Nefedov
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p. 2334 - 2335
(2007/10/03)
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- First gas-phase detection of dimethylstannylene and time-resolved study of some of its reactions
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Using a laser flash photolysis/laser probe technique, we report the observation of strong absorption signals in the wavelength region 450-520 nm (highest intensity at 514.5 nm) from four potential precursors of dimethylstannylene, SnMe2, subjected to 193 nm UV pulses. From GC analyses of the gaseous products, combined with quantum chemical excited state CIS and TD calculations, we can attribute these absorptions largely to SnMe2, with SnMe4 as the cleanest source of the species. Kinetic studies have been carried out by time-resolved monitoring of SnMe2. Rate constants have been measured for its reactions with 1,3-C4H6, MeC, CMe, MeOH, 1-C4H9Br, HCl, and SO2. No evidence could be found for reaction of SnMe2 with C2H4, C3H8, Me3SiH, GeH4, Me2GeH2, or N2O. Limits of less than 10-13 cm3 molecule-1 s-1 were set for the rate constants for these latter reactions. These measurements showed that SnMe2 does not insert readily into C-H, Si-H, Ge-H, C-C, Si-C, or Ge-C bonds. It is also unreactive with alkenes although not with dienes or alkynes. It is selectively reactive with lone pair donor molecules. The possible mechanisms of these reactions are discussed. These results represent the first visible absorption spectrum and rate constants for any organo-stannylene in the gas phase.
- Becerra, Rosa,Boganov, Sergey E.,Egorov, Mikhail P.,Faustov, Valery I.,Krylova, Irina V.,Nefedov, Oleg M.,Walsh, Robin
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p. 7555 - 7562
(2007/10/03)
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- Photochemistry of trimethyltin iodide in polar media: Orbital parentage and observed reactivity
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(CH3)3Snl exists as individual tetrahedral molecules in hexane but reacts with the silanol moieties present on the surface of porous glass and with the hydroxyl group of ethanol and hexanol to form five-coordinate adducts. With the exception of slight shifts to higher energy, formation of the adduct has little effect on the electronic spectrum of the complex, and the wavelength and O2 dependencies of the quantum yield of (CH3)3Snl disappearance indicate that the photochemistry of the complex initiates from the ligand-to-metal charge-transfer (LMCT) state populated on absorption in each medium. Nevertheless, 254 nm excitation in hexane leads to l2 and ((CH3)3Sn)2, whereas excitation of the five-coordinate adduct on the glass surface leads to l2, l3-, ((CH3)3Sn)2, and (CH3)3Sn-OSi≡ (OSi≡ represents a surface siloxyl), while in ethanol, l3- is the only detectable product. Regardless of the medium, the ground state is polarized and population of the LMCT state creates a more uniform charge distribution from which homolytic cleavage of the (CH3)3Sn-l bond is the dominant reaction pathway in each medium. In hexane, the (CH3)3Sn? and l? radicals couple to form ((CH3)3Sn)2 and l2, whereas adsorbed onto the glass, a fraction of the radical pairs thermalize via electron transfer to form l3- and a surface-bound (CH3)3Sn-OSi≡ species. In ethanol, excitation of the solvent adduct (CH3)3Sn-OHC2H5 leads to homolytic cleavage and l2 formation, which reacts thermally with (CH3)3Sn-OHC2H5 to form an [(CH3)3Sn+, l3-] ion pair.
- Dong, Jinquan,Devi, P. Sujatha,Sunil,Mendoza, Edgar,Gafney, Harry D.
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- Phenols as starting materials for the synthesis of arylstannanes via SRN11
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Phenols are converted into aryl diethyl phosphate esters (ArDEP), which on reaction with sodium trimethylstannide (1) or sodium triphenylstannide (2) in liquid ammonia afford arylstannanes by the SRN1 mechanism. Thus, the photostimulated reaction of phenylDEP (3), (4-methoxyphenyl)DEP (4), (4-biphenyl)DEP (5), (1-naphthyl)DEP (6), (2-naphthyl)DEP (7), and 2- (34), 3- (32), and (4-pyridyl)DEP (35) with 1 leads to monostannylated product in fair to excellent yields (20-98%). Also, substrates containing two or three leaving groups react with 1 under irradiation, affording the corresponding di- or tristannylated aryl compounds. With tetraethyl m-phenylene bisphosphate (15), tetraethyl p-phenylene bisphosphate (21), (4-chlorophenyl)DEP (22), and 1,3,5-tris(diethylphospho)benzene (30), the di- or trisubstitution products 1,3-bis(trimethylstannyl)benzene (19) (79%), 1,4-bis(trimethylstannyl)benzene (23) (95 and 97%), and 1,3,5-tris(trimethylstannyl)benzene (31) (57%) are obtained, respectively. Also, the reaction of 6 and 7 with 2 leads to substitution products in quantitative yields, and the reaction of 21, 22, and (4-bromophenyl)DEP (24) with 2 affords 1,4-bis(triphenylstannyl)benzene (38) in high yields (70-100%). On the other hand, the results obtained in the photostimulated reaction of 24 and (4-iodophenyl)DEP (25) with 1, as well as in the reaction of 25 with 2, clearly indicate a fast HME reaction.
- Chopa, Alicia B.,Lockhart, María T.,Dorn, Viviana B.
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p. 1425 - 1429
(2008/10/08)
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- Reactions of lithium hydridosilylamides Me2(H)Si-N(Li)R (R = CMe3, SiMe3) with chlorotrimethylstannane and chloromethylsilanes Me4-n SiCln (n = 1 - 3)
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The under reflux conditions in n-octane stable lithium hydridosilylamides Me2(H)Si-N(Li)R (1: R = CMe3, 2: SiMe3) were allowed to react with chlorotrimethylstannane and chloromethylsilanes Me4-nSiCln (n = 1 - 3) in different molar ratios. 1 reacts with Me3SnCl in n-pentane to give the cyclodisilazane [Me2Si-NCMe3]2 (3) and Me3SnH. The reaction of 2 with Me3SnCl under the same conditions leads to a mixture of Me2 (H)Si-N(SnMe3)SiMe3 (5), [Me2Si:NSiMe3]2 (4), and to Me3SnH. In the reactions of 1 and 2 with chlorotrimethylstannane in tetrahydrofuran the corresponding N-stannylation products Me2(H)Si-N(SnMe3)R 5, 6 and very small amounts of(Me3Sn)2 are formed. The results of the reactions of 1 and 2 with Me2SiCl2 and of 1 with MeSiCl3 in n-hexane show that hydrogen-chlorine-exchange proceeds between the reactants. With Me2SiCl2 the corresponding cyclodisilazanes [Me2Si-NR]7 3, 4, N-silylation products Me2(H)Si-N(SiMe2Cl)R 7b, 8b, and Me2(H)Si-N(SiMe2H)R 7c, 8c, and the silanes Me2SiHCl and Me2SiH2 are formed, the cyclodisilazanes being the main products. 1 and MeSiCl3 produce 3, Me2(H)Si-N(R1)CMe3 (7d: R1 = SiMeCl2, 7e: R1 = SiMeClH, 7f: R1 = SiMeH2) and MeSiH3. In comparison with the reaction of 1 with Me2SiCl2 the yield of cyclodisilazane is smaller and that of N-silylated compounds is higher. The reaction behaviour of 1 towards Me2SiCl2 and MeSiCl3 in THF is comparable to that in n-hexane. No silanimine intermediates are observed in the reactions of 1 or 2 with the chloromethylsilanes Me4-nSiCln (n = 1 - 3) in the molar ratios 1:5 and 1:10.
- Schneider, Jan,Popowski, Eckhard,Peulecke, Normen
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p. 924 - 934
(2007/10/03)
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- Novel heteroleptic stannylenes with intramolecular O,C,O-donor stabilization
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The heteroleptic organotin(II) halides {2,6-[P(O)(OEt)2]2-4-tert-Bu-C6H2}SnX (1, X = Cl; 2, X = Br) have been prepared starting from {2,6-[P(O)(OEt)2]2-4-tert-Bu-C6H2}Li and SnX2 and have been used as precursors for the preparation of the heteroleptic stannylenes {2,6-[P(O)(OEt)2]2-4-tert-Bu-C6H2}SnX (4, X = SPh; 5, X = CH(SiMe3)2; 6, X = SiPh3; 7, X = SnPh3; 7a, X = SnMe3), the tetravalent monorganotin derivatives {{2,6-[P(O)(OEt)2]2-4-tert-Bu- C6H2}SnCl(μ-S)}2 (8) and {2,6-[P(O)(OEt)2]2-4-tert-Bu-C6 H2}SnBr3 (9), the diorganotin cation {2,6-[P(O)(OEt)2]2-4-tert-Bu-C6 H2}(Ph3C)(Cl)Sn+PF6- (10), and the metal-stannylene complexes {2,6-[P(O)(OEt)2]2-4- tert-Bu-C6H2}(Cl)Sn[M(CO)n] (11, M = W, n = 5; 12, M = Cr, n = 5; 13, M = Fe, n = 4). Multinuclear (1H, 13C, 31P, 119Sn) NMR of all compounds, 119Sn Mossbauer spectra of 1 and 10, and single-crystal X-ray structure analyses of 6, 8, and 12 are reported. The derivatives 6, 7, and 7a are rare examples of compounds containing Sn-(II)-Si(IV) and Sn(II)-Sn(IV) bonds, respectively.
- Mehring, Michael
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p. 4613 - 4623
(2008/10/08)
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- Vibrational and electronic spectra of tetrahedral molecules (Me3M)4M′ (M=Si, Sn; M′=Si, Ge) with heteronuclear M-M′ bonds
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Raman, infrared and UV spectra of tetrahedral molecules (Me3Si)4Ge (I), (Me3Sn)4Ge (II), and (Me3Sn)4Si (III) were obtained. To assign and analyze vibrational modes, model normal coordinate calculations for (C3M)4M′ moieties were carried out. Stretching vibrations of heteronuclear tetrahedra M4M′ were studied comparatively. Solid substances I-III were found to undergo an order-disorder phase transition between an ordered crystalline phase and a plastic mesophase (II and III on heating to ca. 65°C while I on cooling to ca. -45°C).
- Leites,Bukalov,Garbuzova,Lee,Baskir,Egorov,Nefedov
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- Ultrasonic Effects on Electroorganic Processes. Part 9. Current Efficiency and Product Selectivity in the Electroreduction of Alkyl Halides to Alkyl Stannanes at a Reactive Tin Cathode
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The ultrasonic effects on the electroreduction of methyl and allyl halides (RX) to the corresponding stannanes (R3SnSnR3 and R4Sn) at a reactive (consumable) tin cathode were examined. The current efficiency and product selectivity for the reduction were found to be greatly affected by ultrasonic irradiation. For instance, the selectivity for (CH3)3SnSn(CH3)3 to (CH3)4Sn from CH3I was significantly increased under irradiation. This fact is rationalized as being due to because the intermediate species [(CH3)3Sn·] formed by the primary one-electron reduction of CH3I are activated for their coupling by mobilization on/from the cathode surface under irradiation. On the other hand, the ultrasonic effects on the reduction of CH3Br and C3H5Br seemed to be slightly different from those in the reduction of CH3I.
- Atobe, Mahito,Nonaka, Tsutomu
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p. 397 - 402
(2007/10/03)
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- Synthesis and dynamic properties of cycloheptatrienyl(dipropyl)borane. Equilibrium with 7-dipropylborylnorcaradiene
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The synthesis of cycloheptatrienyl(dipropyl)borane (2a) was accomplished via the exchange reaction of trimethyl(cycloheptatrienyl)tin (6) and dipropylchloroborane. Compound 2a was found by NMR spectroscopy to equilibrate with its valence tautomer 7-exo-(d
- Gridnev, Ilya D.
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p. 1034 - 1043
(2007/10/03)
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- Photoinduced Reactions of Tri-terf-butylindium with (Diethylamino)trimethylstannane and (Di-n-butylamino)trimethylstannane
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The preparations of [(t-Bu)2InNEt2]2 and [(t-Bu)2InN(n-Bu)2]2 by the photoinduced reactions of (t-Bu)3In with Et2NSnMe3 and (n-Bu)2NSnMe3, respectively, have been investigated. The isolation and characterization of products other than [(t-Bu)2InNE2]2 in these reactions clearly indicate that the reactions of (t-Bu)3In with R2-NSnMe3 do not proceed by simple alkyltrimethyltin elimination. A possible radical mechanism for the formation of the byproducts has been suggested. X-ray crystallographic studies indicate that both compounds are dimeric in the solid state. Crystallographic data: for [(t-Bu)2InNEt2]2 orthorhombic space group Pbca (No. 61), a = 19.135(7) A, b = 19.670(6) A, c = 15.793(7) A, V = 5944.41(5) A3 p(calcd) = 1.346 g cm-3; for [(t-Bu)2InN(n-Bu)2]2, triclinic space group P1 (No. 2), a = 11.943(2) A, b = 15.790(1) A, c = 10.711(3) A, α = 98.60-(1)°,β= 103.54(2)°, V = 94.85(1)°, V = 1926 A3 p(calcd) = 1.232 g cm-3. Mass spectrometry data indicate that both compounds exist as dimers in the gaseous state.
- Freeman, Daniel L.,Odom, Jerome D.,Rodger Nutt,Lebioda, Lukasz
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p. 2718 - 2722
(2008/10/09)
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- Synthesis and reactivity of germanium heterocycles containing germanium - tin bonds
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Previously unknown stannyl-substituted germanium heterocycles, 1,1-bis(trimethylstannyl)-2,3,4,5-tetraphenyl-1-germacyclopenta-2,4-diene and 1,1-bis(trimethylstannyl)-3,4-dimethyl-1-germacyclopent-3-ene were synthesized, and their photolysis and chemical
- Nosov,Lalov,Borovik,Lee,Egorov,Nefedov
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p. 2623 - 2626
(2007/10/03)
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- Tribenzacepentalene dianion and 4,7-disubstituted tribenzodihydroacepentalene derivatives: Formation, reactions, and structural properties of potential tribenzacepentalene precursors
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Upon treatment of tribenzotriquinacene (4a) (R = H) and its centro-alkyl-substituted derivatives 4b-d (R = CH3, C2H5, CH2Ph) with the strongly basic mixture of n-BuLi and KOtPen, 2-fold deprotonation combined with (formal) elimination of RH from positions C(1)-C(10) occurs to generate tribenzacepentalene dianior, 5-K2 with varying ease. Diamon 5-K2 can be trapped with various electrophiles to give 4,7-disubstituted tribenzodihydroacepentalenes 6c-f in good yields. Compounds 6a-f contain an extremely out-of-plane bent C(1)=C(10) double bond, as shown by X-ray structure analyses of 6b-d, and therefore possess an increased reactivity. 4,7-Dihydrotribenzacepentalene (6a) obtained upon protonation of 5 at -78 °C dimerizes at higher temperatures (≥0 °C) toward the head-to-head [2 + 2] dimer 22. At elevated temperatures (≥220 °C), 22 is cleaved to regenerate 6a which can be trapped with anthracene and tetracyclone to give the highly condensed Diels-Alder adducts 23 and 24. Likewise, 6a generated from 5 at low temperatures can be trapped with 1,3-diphenylisobenzofuran, yielding 25. X-ray structure analyses of dimer 22 and adduct 23 revealed strongly elongated 1,1,2,2-tetraarylethane C-C bond, which are attributed to through-bond π-σ* coupling, in these rigid frameworks. The 4,7-bis(trimethylstannyl)-tribenzodihydroacepentalene (6f) undergoes clean transmetalation with methyllithium to give pure dilithium tribenzacepentalenediide (5-Li2.) Crystal structure analysis reveals that the dianionic fragments 5-Li2 in these solvent-separated ion pairs are considerably curved.
- Haag, Rainer,Ohlhorst, Bj?rk,Noltemeyer, Matthias,Fleischer, Roland,Stalke, Dietmar,Schuster, Andreas,Kuck, Dietmar,De Meijere, Armin
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p. 10474 - 10485
(2007/10/03)
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- The first synthesis of 1,1,2-tristannylalkenes
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The addition of tin-tin bonds to stannyl alkynes to generate 1,1,2-tristannylalkenes occurs readily in the presence of the catalyst system palladium bis(dibenzylideneacetone)/triethyl phosphite.
- Mitchell, T.N.,Kowall, B.
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p. 127 - 130
(2007/10/02)
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- Free radical and palladium-catalysed hydrostannation of allenes: a comparison
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While free radical hydrostannation of monosubstituted allenes with Me3SnH affords mixtures of varying composition, cyclohexylidene allene is attacked by the stannyl radical preferentially at the central carbon atom.In contrast, palladium-catalysed hydrostannation involves a regioselective attachment of the organotin moiety to the less highly substituted terminal carbon atom of the allene framework.
- Mitchell, Terence N.,Schneider, Ulrich
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p. 195 - 199
(2007/10/02)
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- Addition of stannyl phosphines to alkynes and allenes
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Diphenyl(trimethylstannyl)phosphine adds to alkynes (both terminal and nonterminal) and allenes under free radical conditions.The former reaction occurs regiospecifically with preferential formation of E-isomers, the latter regioselectively.Product identi
- Mitchell, Terence N.,Belt, Heinz-Joachim
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p. 167 - 176
(2007/10/02)
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- Organozinnverbindungen XXXIII. Die erste Komplexbildung zwischen Organozinn- und Nitroderivaten: Reactionen der Zinn-Alkyl-Bindung
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Although trimethylstannylbenzene in presence of MeCOCl*AlCl3 undergoes a carbodestannylation to give acetophenone, its 2-NO2, 3-NO2, 4-NO2, and 2,4-(NO2)2 derivatives (1a-d) exhibit a surprising, high activation of the aliphatic C-Sn bond (Me-Sn) which allows a single cleavage to give the corresponding dimethylchlorostannyl nitrobenzenes (2a-d) quantitatively without any aryl-Sn bond cleavage.A strong, hitherto unknown, intramolecular pentacoordination at the tin in 2a and 2d via complexation by the ortho nitro groups, is indicated by the IR, 1H, 13C, and 119Sn NMR spectral data.In contrast, reaction of iodine with 1a-d, or with 2a-d results in exclusive SEar ipso substitution of all stannyl groups.The mechanisms are discussed, preparative procedures and spectroscopic details are described.
- Al-Allaf, Talal A. K.,Kobs, U.,Neumann, W. P.
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- Selective Metalation of Bicycloocta-2,6-diene, II. Distannylated Derivatives and Stannylated Tricyclic Secondary Products
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Distannylated bicycloocta-2,6-diene (1) with (CH3)3Sn groups in positions exo-4 and 7 (7a), endo-4 and 7 (7b), exo-4 and 6 (7c), and probably exo-4 and endo-4 (7d) are obtained when 1 is treated first with an excess of n-BuLi/t-BuOK in alkane and then with (CH3)3SnCl.Byproducts are monostannylated derivatives of 1 and 1,4-bis(trimethylstannyl)but-2-ene (3).The formation of 7a/b/c is best understood when the two possible bicycloocta-2,6-dienyl dianions are generated as intermediates. 3, exo-4-Bis(trimethylstannylbicycloocta-2,6-diene (7e) is obtained from the corresponding dibromo derivative of 1 and (CH3)3SnLi with 3-bromo-exo-4-trimethylstannylbicycloocta-2,6-diene (9) as an intermediate.The bicyclic stannyl compounds are susceptible to a 1,5-homopentadienyl shift of a (CH3)3Sn group at relatively low temperature when the starting compound has the stannyl group in position 4 of 1 and when positions 6 or 7 are unsubstituted.Tricyclo2,7>oct-3-enes with (CH3)3Sn groups in positions exo-6 (5a), endo-6 (5b), 3 and exo-6 (10a), and 3 and endo-6 (10b) are thus obtained.On further heating, 10b gives 1-trimethylstannyl-3-vinylbenzene (11).All compounds have been studied systematically by NMR spectroscopy including δ(119Sn), δ(13C), δ(1H), 4/5J(119/117Sn-119Sn), nJ(119/117Sn-13C), nJ(119/117Sn-1H), 1J(13C-1H), and nJ(1H-1H).Among all nuclei, 119Sn gives the most simple spectra.From the 13C NMR spectra a series of useful increments of (CH3)3Sn groups emerges.The most interesting coupling constants are 5J(119/117Sn-119Sn), for which a considerable change with the dihedral angle is established, and nJ(119/117Sn-13C). For n = 3 and 4 the latter are especially useful because their angular dependence leads to unambiguous signal assignments. - Keywords: Bicycloocta-2,6-diene, Double Deprotonation, Stannyl Derivatives, Tricyclo2,7>oct-3-ene Derivatives, 119Sn, 13C, 1H NMR Spectra
- Hertkorn, N.,Koehler, F. H.
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p. 1405 - 1415
(2007/10/02)
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- Reaction of Me3SnCu*Me2S with terminal alkynes. Preparation of 2-trimethylstannyl-1-alkenes
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Reaction of ω substituted terminal alkynes 5 with (trimethylstannyl)copper(I)-dimethyl sulfide (1) under suitable reaction conditions provides good to excellent yields of the corresponding 2-trimethylstannyl-1-alkenes 6.
- Piers, Edward,Chong, J. Michael
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p. 1425 - 1429
(2007/10/02)
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- Reactions of organotin hydrides with lithium diisopropylamide and organolithiums. Reactivities of the intermediates and of the lithium hydride produced
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Equimolar lithium diisopropylamide (LDA) and trimethyltin hydride (TMTH) react in tetrahydrofuran (THF) to form diisopropylamine and (trimethylstannyl)lithium, but in diethyl ether or hexanes 2 mol of TMTH is required for complete reaction and the products are diisopropylamine, hexamethylditin, and lithium hydride. When organic halides are present in this reacting system, reduction to alkane or substitution to form the trimethylalkyltin may occur depending on the nature of the halide. These and other observations suggest that (trimethylstannyl)lithium is formed as an intermediate yielding the tetraalkyltin. Studies on the products and stoichiometries of the reductions of alkyl bromides in ether and hexanes suggest that three reducing agents may be involved: TMTH, [Me3Sn(H)N-i-Pr2]-, and [Me3SnSn(H)Me3]-. The latter predominates in ether, and either or both of the others predominate in hexanes. Formation of methylcyclopentane from 1-bromo-5-hexene suggests involvement of a free radical mechanism. When methyllithium is used instead of LDA in the reaction with TMTH, the products are tetramethyltin and lithium hydride. This reaction can also be diverted to reduction by the presence of primary bromides. Aryl bromides react in both systems, but the yields of either substitution or reduction products are low. The lithium hydride formed in these reactions is extremely reactive as a base as shown by a brief study of its reaction with weak carbon acids and amines and as a nucleophile by its reaction with hexamethylditin to form (trimethylstannyl)lithium in THF.
- Reimann, Werner,Kuivila, Henry G.,Farah, Dan,Apoussidis, Theodorus
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p. 557 - 565
(2008/10/08)
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- Reactions of Trialkylstannane Anions R3Sn- with Arylstannanes ArSnR'3
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The reactions of trialkylstannane anions R3Sn- with arylstannanes ArSnR'3 have been investigated; trialkylstannane anions with arylstannanes at 50 deg C gave substitution products ArSnR3 in good yields.Most of these substitution products are diverted to r
- Mochida, Kunio
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p. 3299 - 3306
(2007/10/02)
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- The Reaction of Calcium Atoms with Group 4B Catenates, Me3E-E'Me2R (E, E'=Si, Ge, Sn; R=Me, Cl)
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Calcium atoms are thought to be inserted into E-E' bonds of group 4B catenates, Me3E-E'Me2R (E, E'=Si, Ge, Sn; R=Me, Cl) to give the corresponding Me3E-Ca-E'Me2R compounds.
- Mochida, Kunio,Yamanishi, Takayuki
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p. 3429 - 3430
(2007/10/02)
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- The Metalation of N,N,N',N'-Tetramethylethylenediamine (TMEDA)
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TMEDA may be metalated with good regioselectivity: tert-BuLi attacks preferably a methyl group whereas a methylene group is deprotonated by n-BuLi/tert-BuOK.Thus, trapping with Me3SnCl and hydrolytic work-up give either 53percent of Me2N2NMe(CH2SnMe3) (2) and 5percent of (Me3Sn)(Me2N)C=CH2 (3) or 3 alone (42percent), respectively. 3 is formed from deprotonated TMEDA by elimination of amide which can be trapped as Me2N(SnMe3) (5); some trans-(Me3Sn)CH=CH(NME2) (4) is also obtained.The structures of the compounds follow mainly from 1H-, 13C-, 15N-, and 119Sn-NMR data.
- Koehler, Frank H.,Hertkorn, Norbert,Bluemel, Janet
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p. 2081 - 2082
(2007/10/02)
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- PALLADIUM CATALYSIS IN ORGANOTIN CHEMISTRY: ADDITION OF HEXAALKYLDITINS TO ALKYNES
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Tetrakis(triphenylphosphine)palladium(0) catalyses the cis-addition of hexaalkylditins R6Sn2 (R = Me, Et, Bu) to acetylene and 1-alkynes; for R = Bu, however the reaction is not quantitative.With very few exceptions there is no reaction in the case of non
- Mitchell, T.N.,Amamria, A.,Killing, H.,Rutschow, D.
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p. 257 - 266
(2007/10/02)
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- 1,1-Distannyl 1-alkenes: A new method of formation and some further reactions
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1,1-Distannyl-1-alkenes of the type RR′C=C(SnMe3)2 can be readily prepared from (trimethylstannyl)lithium and geminal dibromoalkenes. An extension of this method to include the preparation of vicinal distannylalkenes is in general not possible. Hydrostannation of the geminal distannylalkenes gives tristannylalkanes; bromodestannylation using N-bromosuccinimide occurs readily, as does halodemethylation at tin using dimethyltin dihalides. Palladium-catalyzed coupling reactions between geminal distannylalkenes and organic halides are possible, but stereoselective monocoupling is probably not realizable. Selected multinuclear NMR data for the compounds prepared are presented.
- Mitchell,Reimann
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p. 1991 - 1997
(2008/10/08)
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- Palladium(0)-mediated Insertion of Isonitriles into the Silicon-Tin Bond
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Insertion of isonitriles into the silicon-tin bond of organosilylstannanes is catalysed by palladium(0) to give organosilyl(N-substituted imino)stannanes.
- Ito, Yoshihiko,Bando, Takashi,Matsuura, Takaharu,Ishikawa, Mitsuo
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p. 980 - 981
(2007/10/02)
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- DIE CHEMIE DER SCHWEREN CARBEN-ANALOGEN R2M, M=Si, Ge, Sn. X. 7-SILA-NORBORNADIENE: REAKTIONEN MIT HALOGENEN UND THERMOLYSE IN GEGENWART VON METALLORGANISCHEN ODER ORGANISCHEN HALOGENIDEN
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The 7-sila-norbornadienes (I-IV) react rapidly with halogens at -20 to +20 deg C to yield Me2SiHal2 (Hal=Cl, Br, I) and the naphthalene or benzene derivatives (V-VIII).Bromine in CCl4 at 0 deg C, however, caused surprising rearrangement in I giving the 2-bromosilylated naphthalene (IX), since an attack at the alkene group seemed to be preferred.Methylation and methoxylation of IX gave respectively X and XI.Careful hydrolysis of IX yielded the disiloxane XII.Insertions of Me2Si into the Si-Hal, Si-H, Si-C, or Sn-C bonds were not observed at 160-200 deg C, whereas insertions into Sn-Cl or Sn-H bonds occurred smoothly via a one-step mechanism.Halogen is abstracted from different C-Hal bonds leading to Me2SiHal2 and sometimes to Me4Si2Hal2.The degradation of the silylene precursors in these cases is always first order and resembles that of spontaneous thermolysis.
- Appler, Hubertus,Neumann, Wilhelm P.
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p. 247 - 260
(2007/10/02)
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- REACTIONS OF (CH3)3SnM(CH3)3 (M = Si; Ge) WITH CHLOROTRIMETHYLSTANNANE AND DICHLORODIMETHYLSTANNANE IN METHANOL SOLUTION
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The reactions of (CH3)3SnM(CH3)3 for M = Si and Ge with (CH3)3SnCl or (CH3)2SnCl2 in methanol follow the same path as the corresponding reactions of (CH3)6Sn2, and involve Sn-CH3 cleavage at essentially the same rate.Complications arise from reaction of H
- Cuthberston, Matthew J.,Wells, Peter R.
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- Coupurs par transfert d'electrons de la liaison Sn-CH2 dans les composes R3SnCH2X
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In the presence of nucleophiles , the Sn-CH2 bond in organotin iodides R3SnCH2I with R=Me, Et and Ph is cleaved by an ionic mechanism or by an electron-transfer involving R3SnCh2., R3SnCH2CN(1). and R3Sn. radicals which can be induced electrochemically.Dimerisation, reoxydation of reduction of the R3Sn. radical occur depending on the potential, the solvent and the substituent.A complete description of the mechanism led us to study the electrochemical behaviour of R3SnCH2I iodides and resulted in a simple preparation of bis mercury compounds.
- Devaud, Marguerite,Lecat, Jean-Luc
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p. 1187 - 1190
(2007/10/02)
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- NUCLEOPHILIC SUBSTITUTION AT THE BRIDGEHEAD OF 1,4-DIHALOBICYCLOOCTANES : AN ABNORMAL LEAVING GROUP MOBILITY ORDER
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Stannylation of 1-bromo- and 1-chloro-4-iodobicyclooctane with (trimethyltin)lithium indicate an abnormal leaving group mobility (Br>I>Cl).
- Adcock, William,Iyer, V. Sankar,Kok, Gaik B.,Kitching, William
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p. 5901 - 5902
(2007/10/02)
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- Zintl anions from the extraction of zintl phases with non-amine solvents: Isolation of (Me4N)4Sn9, [K(HMPA)2]4Sn9, and K4SnTe4 and structural characterization of (Bu4N)2Mx (M = Te, x = 5; M = Se, x = 6; M = S, x = 6)
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Polyatomic main-group anions like Sn94-, Te52-, Se62-, S62-, and SnTe44- have been isolated without the use of cryptate ligands. The polychalcogenides (Bu4N)2Mx (where M = Te, x = 5; M = Se, x = 6; M = S, x = 6; Bu = n-C4H9) are obtained by the aqueous extraction of binary alkali-metal/main-group alloys in the presence of Bu4NBr. These polychalcogenides are isomorphous and have been structurally characterized by X-ray crystallography. The nonastannide(4-) anion has been isolated both as the tetrakis(tetramethylammonium) compound, [(CH3)4N]4Sn9, and as the HMPA (hexamethylphosphoric triamide) solvate, [K(HMPA)2]4Sn9. Both compounds are somewhat thermally unstable at 25 °C. The compound K4SnTe4 has been isolated by the aqueous extraction of ternary K/Sn/Te alloys.
- Teller, Raymond G.,Krause, Larry J.,Haushalter, Robert C.
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p. 1809 - 1812
(2008/10/08)
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- MECHANISTIC STUDIES ON DECOMPOSITION OF TRIALKYLSTANNYLLITHIUMS
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The fast decomposition of trialkylstannyllithiums, R3SnLi (R=Me, Et and Bu), in the presence of hexaalkyldistannanes, R3SnSnR3, was observed, and its mechanism was investigated kinetically.Partial dissociation of R3SnLi into a complex in a solvent cage is suggested to occur in the initial step.The RLi in the complex can be trapped instantaneously by R3SnSnR3 to afford R4Sn and R3SnLi, and the counterpart R2Sn: by R3SnLi giving R3SnR2SnLi.The decomposition of R3SnLi followed first-order kinetics within 3.5 h, corresponding well to the rate of disappearance of R3SnSnR3 and of appearance of R4Sn.The partial dissociation rate constant (k1) of Me3SnLi into the complex was determined as 2.0*10-3 min-1.The values of k1 are about 100 times those of rate constants (k') for decomposition of R3SnLi in the absence of R3SnSnR3.Reformation of R3SnLi from the complex is highly significant.
- Kobayashi, Kazuko,Kawanisi, Mituyosi,Hitomi, Torazo,Kozima, Sinpei
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p. 299 - 311
(2007/10/02)
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- REACTION OF METHYL AND PHENYL PICRATES WITH NUCLEOPHILES
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The reactions of 2,4,6-trinitroanisole with various nucleophiles Me3SnM, Me3SiLi, BuLi, Me4NBBu4, PhMgI, CN-, lithium (potassium) succinimide, F-, Cl-, Br-, SCN-, NO2-, NO3-, HCO3-, PhSO2-,AcO-, S2- were investigated.It was found that the final products are the picrate and the corresponding methyl derivatives.The formation of intermediate ? complexes was detected in a series of the reactions (Me3SnLi, potassium succinimide, Bu4B-, CN-, NO2-, PhSO2-).Possible mechanisms for the reaction are examined.Reactions of 2,4,6-tricyanoanisole and phenyl picrate with certain nucleophiles were also investigated.
- Artamkina, G. A.,Egorov, M. P.,Beletskaya, I. P.,Reutov, O.A.
-
-
- REACTION OF TRIALKYLSTANNYLLITHIUM AND HEXAALKYLDISTANNANE. 1H AND 119Sn NMR STUDIES
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The reaction of hexamethyldistannane (Me3SnSnMe3) with metallic lithium in tetrahydrofuran (THF) has been studied by 1H and 119Sn NMR spectroscopy.All spectra displayed a single peak which moved gradually from the chemical shift of Me3SnSnMe3 (0.22 ppm in 1H NMR and -108.7 ppm in 119Sn NMR) into those of trimethylstannyllithium (Me3SnLi, -0.37 ppm, -182.7 ppm) in 2 h.A mixture of Me3SnSnMe3 and Me3SnLi in THF also showed only a single peak both in the 1H and 119Sn NMR spectra.There was a linear relationship between the chemical shift of the singlet and the amount of lithium per tri-methylstannyl group (Li/Me3Sn).The equilibration of the Me3Sn group between the two species was proposed as a plausible explanation for the apparent equivalency of Me3Sn and was supported by investigating two mixed alkyl systems.Both the Me3SnLi-Et3SnSnEt3 and Et3SnLi-Me3SnSnMe3 systems showed single Me3Sn and Et3Sn group resonances each in the NMR spectra.The chemical shift of Me3Sn vs. (Li/R3Sn) in 119Sn NMR spectra, however, deviated considerably to higher field from the linear relationship, while that of Et3Sn shifted to lower field.This can be interpreted in terms of the rapid exchange between Me3Sn and Et3Sn in the following two equilibria.
- Kobayashi, Kazuko,Kawanisi, Mituyosi,Kozima, Sinpei,Hitomi, Torazo,Iwamura, Hiizu,Sugawara, Tadashi
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p. 315 - 328
(2007/10/02)
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