- Alkyl- and acyl-substituted vinylstannanes: Synthesis and reactivity in electrophilic substitution reactions
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Six substituted vinylstannanes have been prepared. (E)- and (Z)-2-trimethylstannyl-2-butene, (1) and (2), respectively, 2-methyl-1-(trimethylstannyl) propene, (3), and 3-methyl-2-trimethylstannyl-2-butene, (4), were prepared by coupling the appropriate lithium or Grignard reagent with chlorotrimethylstannane. 3-Trimethylstannyl-3-butene-2-one, (5), and (Z)-3-trimethylstannyl-3-hexene-2-one, (6), were prepared by palladium(O) catalyzed hydrostannation of the appropriate ynone. This reaction was regiospecific such that the trimethylstannyl and carbonyl groups were bonded at the same vinyl carbon. The reaction was also stereospecific giving syn addition in each case. However, isomerization to a mixture of isomers was observed for the reaction of (5) with Me3SnD and complete isomerization of E-(6) to Z-(6). Each compound was characterized by 1H, 13C, and 119Sn NMR. The reactivity to protodestannylation was determined for each compound by spectrophotometric measurement of second order rate constants. The reactivity of the multimethyl-substituted vinylstannanes was consistent with the reactivity determined previously for monomethyl-substituted vinylstannanes. However, two methyl groups at the remote vinyl carbon exhibited a synergistic activating effect on the protodestannylation reactivity. The acyl group was found to be deactivating for protodestannylation. The stereochemistry of the reaction was round to take place with retention of configuration.
- Cochran, John C.,Prindle, Vicki,Young, Heather A.,Kumar, Mark H.,Tom, Samson,Petraco, Nicholas D. K.,Mohoro, Clare,Kelley, Brendan
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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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- Reagents based on cyclopentadienyl derivatives of the group 14 elements for the synthesis of indium(I) derivatives. Crystal and molecular structure of in(C5H4SiMe3)
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Cyclopentadienyl trimethyl derivatives of the group 14 elements (C5H4MMe3, M = Si, Ge, Sn) have been investigated for their effects on indium(I) chemistry. The compounds In(C5H4SiMe3) and In(C5H4GeMe3) have been prepared from the corresponding lithium cyclopentadienyl reagent LiC5H4MMe3 and InCl. Characterization data have included partial elemental analyses (C, H), physical properties, IR and 1H NMR spectroscopic data, oxidation reactions with dilute aqueous HCl, and a single-crystal X-ray structural study in the case of In(C5H4SiMe3). When cyclopentadienyltrimethyltin, C5H5SnMe3, was combined with InCl in diethyl ether, In(C5H5) and Me3SnCl were formed in good yields. In(C5H4SiMe3) crystallizes in the centrosymmetric monoclinic space group P21/c (C2h5; No. 14) with a = 9.171 (5) ?, b = 9.910 (6) ?, c = 11.677 (7) ?, β = 97.30 (5)°, V = 1052.6 (11) ?3, and Z = 4. Diffraction data (Mo Kα radiation, 2θ = 4.5-50.0°) were collected on a Syntex P21 automated four-circle diffractometer, and the structure was solved and refined to RF = 5.0% and RwF = 4.0% for all 1851 independent reflections (RF = 3.1% and RwF = 3.5% for those 1336 data with |Fo| > 6σ|Fo|)). The solid-state structure consists of infinite zigzag chains of [In(C5H4SiMe3)]∞. Each indium atom interacts with two η5-C5H4SiMe3 ligands with a centroid?In?centroid angle of 131.78°, and each η5-C5H4SiMe3 ligand is linked to two indium atoms with In?centroid?In angles of 175.94°. There are no short interstrand In?In interactions, the shortest such distance being 5.428 ?. Thus, In(C5H4SiMe3) is the first cyclopentadienylindium(I) derivative with no apparent indium-indium interactions.
- Beachley Jr.,Lees,Glassman,Churchill, Melvyn Rowen,Buttrey, Lisa A.
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- Investigation of the catalyst system tungsten hexachloride/tetramethyltin; reduction of tungsten hexachloride during the alkylation step
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The alkylation steps in the catalyst system tungsten hexachloride/tetramethyltin have been studied kinetically. FTIR examinations in combination with UV and GC results have shown that the alkylation of tungsten hexachloride is accompanied by a reduction of the tungsten component. Ether addition increases the amount of the tungsten chloride which is reduced.
- Thorn-Csanyi, E.,Kessler, M.
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- Donor-Acceptor Complexes of Organometals and Iodine. Alkyl Ligands as Probes for Steric Effects in Charge Transfer
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Charge-transfer (CT) absorptions are observed between iodine and a variety of homoleptic alkylmetals including dialkylmercury (R2Hg) and tetraalkylmetals (R4M) of the group 4A elements (where M = lead, tin, germanium, and silicon) in carbon tetrachloride solutions.These alkylmetal-iodine complexes are all classified as weak, the formation constants, K, being generally less than 5 M-1 for dialkylmercury and less than 3 M-1 for the methylethyllead compounds.The formation constants of tetraalkyltin, -germanium, and -silicon are too small to measure (K -1).The frequency of the charge-transfer bands (hνCT) varies lineary with the vertical ionization potential (ID) of the alkylmetal, determined independently from the photoelectron spectra.However, two separate correlations are required for these alkylmetals-one for the series of two-coordinate, linear dialkylmercury compound and another for the series of four-coordinate, tetrahedral tetraalkylmetals corresponding to a sterically open and a quasi-spherical configuration of electron donors, respectively.Steric effects in these alkylmetal-iodine complexes may be evaluated in two ways.By the direct method, the role of steric effects in determining the charge transfer transition energy is associated with the Coulombic term (e2/rDA) in the first-order treatment of weak complexes according to the Mulliken theory.The mean separation rDAin the CT complexes of R2Hg and R4M, calculated from the measured values of βCT, ID, and the vertical electron affinity of iodine, shows two paralell trends, both increasing with decreasing values of the ionization potentials.This behavior is the same as that evaluated for the CT complexes of tetracyanoethylene (TCNE) with the same series of alkylmetals, in which K is larger and can be measured for as well as complexes.By the indirect method, steric effects are evaluated relative to a reference alkylmetal (Me2Hg for R2Hg and Me4Sn for R4M).The difference ΔE, taken as the relative change in steric effects, is shown to be essentially the same in TCNE and iodine complexes.The later bears on the general question as to whether small (intermediant) values of K (-1) or -ΔH (-1) can be used as adequate criteria for contact charge transfer.
- Fukuzumi, S.,Kochi, J. K.
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- Aryltrimethylstannane Cation Radical Fragmentation Selectivities That Depend on Codonor: Evidence for Reactions from Heterodimer Cation Radicals
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The aryl/methyl fragmentation selectivities for the photooxidations of phenyltrimethylstannane and (4-methylphenyl)trimethylstannane by 1,2,4,5-tetracyanobenzene in acetonitrile were found to depend on the codonor used to generate the stannane cation radi
- Luo, Pu,Dinnocenzo, Joseph P.
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- Supramolecular host-guest coordination systems: [(G+)(Me3E)3MII(CN) 6]∞ as ion exchangers, where (G+=Me3E, Et4N or stp), (E=Sn or Pb) and (M=Fe or Ru)
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A number of 3D-coordination polymers, constructed via [dM(CN)6] building blocks and (Me3E) connecting units, have been prepared and characterized by X-ray powder diffraction and different spectroscopic methods. 1-Methyl-4-(4′-R-styryl) or (2′-R-styryl) pyridinium cations (stp) have been successfully encapsulated within the expandable wide channels of the 3D-coordination polymers by tribochemical or ion exchange reactions producing novel molecular composites. Apart from 6, [(4′-OCH3-stp)(Me3Sn)3Fe II(CN)6-MeOH]∞ which exhibits thermochromic behaviour, the molecular composites [(stp)x(Me3E)3FeIII 1-xFeIIx(CN)6]∞, 1-12 are mixed valence materials exhibiting localized interaction between the mixed valence iron. The results indicated an ion charge transfer interaction between the guest stp-cations and the host matrix. The molecular composites [(stp)(Me3E)3 MII(CN)6]∞, 13-18 are due to the facile readiness of the coordination polymers [(Me3E)4M(CN)6]∞ and [(Et4N)(Me3Sn)3Fe(CN6)] ∞ to ion exchange. Elsevier Science Ltd.
- Ibrahim, Amany M.A.
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- Simple procedure for conversion of a trialkyltin fluoride into the corresponding chloride or bromide
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Trialkyltin fluorides are converted into the chlorides or bromides on treatment with an excess of the corresponding sodium halide in tetrahydrofuran.
- Mitchell, Terence N.,Kwetkat, Klaus,Godry, Bernd
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- Electon-Transfer, Halogen-Metal Exchange and Direct Processes in Formal Nucleophilic Substitutions on Alkyl Halides by Trimethyltinsodium
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Formal nucleophilic substitutions have been studied by simple trapping techniques designed to separate and estimate contributions of reactions proceeding by way of free radicals, by way of anions, and by way of geminate or synchronous processes.Reactions of trimethyltinsodium with organic halides in tetrahydrofuran at 0 deg C were examined, using dicyclohexylphosphine for trapping free radicals and tert-butylamine for free anionoids.Among 22 halides included in this study nine have been shown to involve two or all three of the mechanistic pathways.Primary chlorides reacted predominantly by a direct mechanism (SN2, geminate reaction of intermediates, or multicenter process).Branching, as in isobutyl and neopentyl, led to contributions from electron-transfer (free radical) and halogen-metal exchange (anionoid) mechanisms.Secondary bromides reacted predominantly by the ET process (major) and HME (minor) while the relative contributions from these were reversed in importance with the iodides.Triethylcarbinyl chloride reacted exclusively by elimination while the bromide reacted by ET alone or in competition with elimination. 1- and 2-bromoadamantanes reacted by ET, and 1-chloroadamantane showed no reaction after 10 days at -4 deg C.
- Smith, Gary F.,Kuivila, Henry G.,Simon, Reyna,Sultan, Leslie
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- Redox properties of dihalogermylenes, dihalostannylenes and their complexes with Lewis bases
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Reduction and oxidation potentials of Gel2, GeBr2 * B (B = dioxane, PPh3), GeCl2 * B (B = dioxane, PPh3, AsPh3, Py, dip), SnCl2 * dioxane, SnX2 (X = F, Cl Br, I) were measured in MeCN at 20 deg C.The data obtained indicate that in many cases the EX2 and EX2 * B (E = Ge, Sn) can act not only as a good reducing agents, but also as strong oxidants.Examples of redox reactions in which EX2 and EX2 * B react as oxidizing agents were found.The variation of the redox potentials of the dihalogermylenes and dihalostannylenes with complexation and with the nature of the halogen substituent and the Lewis base is discussed.In some cases (GeI2, GeX2 * B; X = Cl, Br, B = dioxane, PPh3), the reduction or oxidation was found to be quasi-reversible, indicating the presence of relatively stable ion radicals.AM1 calculations on GeCl2 * dioxane and GeCl2 * PH3 complexes show that the complexation destabilizes both the highest occupied and the lowest unoccupied MOs of the carbene analogues.The complexation reduces the IP and lowers the oxidation potential; its intluence on the electron affinity is not straightforward.Calculations of the ion radicals of GeCl2 and GeCl2 * B (B = dioxane, PH3 ) show that in the ground state an unpaired electron occupies ?-MO in the cation and ?-MO in anion radicals.Keywords: Germanium; Tin; Germylenes; Stannylene; Electrochemistry; AM1 calculations
- Lee, V.Ya.,Basova, A.A.,Matchkarovskaya, I.A.,Faustov, V.I.,Egorov, M.P.,et al.
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- Conversion of Alkyltantalum Chlorides to Fluorides Using Trimethyltin Fluoride as a Fluorinating Agent. Crystal Structures of (p-MeC6H4CH2)3TaF2, (Me3SnCl.Me3SnF.TaF5)n, (Me3Si)2CHTaCl4
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The reactions of alkyltantalum chlorides with trimethyltin fluoride were found to be highly dependent on the number of organic ligands on tantalum as well as on the electronic and the steric nature of the substituants. The synthesis of trialkyltantalum difluorides of general formula (RCH2)3TaF2 (R = Ph, 1; R = p-Tol, 2; R = Me3Si, 3) and the first example of the alkyltantalum tetrafluoride (Me3Si)2CHTaF4 (8) are reported. The compounds (p-MeC6H4-CH2)3TaF2, (Me2SnCl.Me3SnFTaF5)n (Me3Si)2CHTaCl4, {(Me3Si)2CHTaCl4(Me3Si) 2CH]2Ta2-Cl6μ2-O)}, and (Me3Si)2CHTaF4 respectively have been characterized by single-crystal X-ray structural analysis.
- Guzyr, Olexandr I.,Schormann, Mark,Schimkowiak, Jürgen,Roesky, Herbert W.,Lehmann, Christopher,Walawalkar, Mrinalini G.,Murugavel, Ramaswarny,Schmidt, Hans-Georg,Noltemeyer, Mathias
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- Precise measurements of 115/117/119Sn NMR frequencies and first observation of isotope-induced chemical shifts 1Δ117/119Sn(15N), 1Δ115/119Sn(15N), and 2Δ117/119
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Tris(trimethylstannyl)amine 1 and trimethylsilyl-bis(trimethylstannyl)amine 2 (both ca. 13% 15N labelled) were studied by 115/117/119Sn-, 15N-, and 29Si NMR spectroscopy. Precise measurements of the Sn NMR frequ
- Wrackmeyer, Bernd,Vosteen, Martina,Storch, Wolfgang
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- STUDY OF THE REDISTRIBUTION REACTION OF TETRAMETHYLTIN WITH DIMETHYLTIN DICHLORIDE IN SEVERAL APROTIC SOLVENTS.
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The redistribution reaction of tetramethyltin with dimethyltin dichloride was studied in eight aprotic solvents by using the **1H NMR technique. The second-order rate constant of the reaction (ln k//2) is proportional to the dielectric constant of the solvent. There is a weak relation between the rate constants (ln k//2) and the values of **2J(Sn-H) of Me//2SnCl//2 in several solvents, which are considered to be related to the coordination ability of the solvents. The rate constants are also related to Kosower's Z values of the solvents. The activation entropies of the reaction in four typical solvents have large negative values. This predicts that the reaction proceeds via a four-center transition state.
- Yamashita,Saito,Yoshino,Takahashi
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- MECHANISM OF THE REACTION OF (ARYLOXY)TRIMETHYLSTANNANE WITH METHANESULFONYL CHLORIDE - SOLVENT AND SUBSTITUENT EFFECTS ON THE RATE OF THE REACTION.
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A kinetic study has been conducted on the reactions of (aryloxy)trimethylstannanes with methanesulfonyl chloride giving chlorotrimethylstannane and aryl methanesulfonates. The reaction was found to obey a second order kinetic equation. The solvent effect on the rate of the reaction appeared obscure although a small rate enhancement was observed in a polar solvent. Substituent effect of the aryloxyl group was found to be dependent on the solvent used while a clear isokinetic relationship was observed. A charge separated four-center transition state has been suggested for the reaction.
- Kozuka,Yamaguchi,Tagaki
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- Platinum-catalyzed phenyl and methyl group transfer from tin to iridium: Evidence for an autocatalytic reaction pathway with an unusual preference for methyl transfer
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Platinum complexes have been found to catalyze the transfer of σ-bound ligands to the Ir center in Cp*(PMe3)IrCl2 (Cp* = η5-C5Me5) from Bu3SnPh and PhxSnMe
- Smith, Stuart E.,Sasaki, Jennifer M.,Bergman, Robert G.,Mondloch, Joseph E.,Finke, Richard G.
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- A utility for organoleads: Selective alkyl and aryl group transfer to tin
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Me4Pb and Ph4Pb readily transfer methyl or phenyl groups to an equivalent molar ratio of tin(iv) chlorides in the order SnCl4 > MeSnCl3 > Me2SnCl2 > Me3SnCl, often in a selective manner. Me3PbCl and Ph3PbCl specifically transfer a single methyl/phenyl group under the same reaction conditions to produce recovered yields in >75%. Specific transfer of 2 methyl groups from PbMe4 can be achieved at elevated temperatures and/or a 2:1 molar ratio Pb:Sn.
- Arias-Ugarte, Renzo N.,Pannell, Keith H.
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p. 1703 - 1708
(2018/02/09)
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- Mechanism and Unusual Fragmentation Selectivities of Aryltrialkylstannane Cation Radicals
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Aryltrialkylstannane cation radicals were generated and characterized by nanosecond transient absorption spectroscopy. Kinetics show the fragmentations of the stannane cation radicals occur by a bimolecular, nucleophile-assisted mechanism (SN2). Consistent with this hypothesis, steric effects on both the nucleophile and the stannane cation radicals were observed. Steady-state, preparative photooxidation experiments show that aryltrimethylstannane cation radicals have an unusual preference for loss of aryl radicals over methyl radicals and that the selectivity for aryl vs methyl radical loss is dependent on the identity of the nucleophile. The preference for loss of aryl radicals is rationalized by a hypothesis based on Bents rules.
- Luo, Pu,Dinnocenzo, Joseph P.
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p. 9240 - 9246
(2015/09/28)
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- Direct Detection, Dimerization, and Chemical Trapping of Dimethyl- and Diphenylstannylene from Photolysis of Stannacyclopent-3-enes in Solution
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Dimethyl- and diphenylstannylene (SnMe2 and SnPh2, respectively) have been successfully detected and characterized in solution. The stannylenes were generated by photolysis of 1,1,3-trimethyl-4-phenyl- (2) and 3,4-dimethyl-1,1-diphenylstannacyclopent-3-ene (3), respectively, which have been shown to extrude the species cleanly and in high (0.6 2SnCl2) as the stannylene substrate. Laser flash photolysis of 2 and 3 in deoxygenated hexanes affords promptly formed transient absorptions assigned to SnMe2 (λmax = 500 nm; ε500 = 1800 ± 600 M-1 cm-1) and SnPh2 (λmax = 290, 505 nm; ε500 = 2500 ± 600 M-1 cm-1), respectively, which decay with absolute second-order rate constants within a factor of 2 of the diffusional limit in both cases. The decay of the stannylenes is accompanied by the growth of new transient absorptions ascribable to the corresponding dimers, the structures of which are assigned with the aid of DFT and time-dependent (TD) DFT calculations at the (TD)ωB97XD/6-31+G(d,p)C,H,O-LANL2DZdpSn level of theory. Dimerization of SnMe2 affords a species exhibiting λmax = 465 nm, which is assigned to the expected Sn=Sn doubly bonded dimer, tetramethyldistannene (Me2Sn=SnMe2, 16a), in agreement with earlier work. In contrast, the spectrum of the dimer formed from SnPh2 exhibits strong absorptions in the 280-380 nm range and a very weak absorption at 650 nm, on the basis of which it is assigned to phenyl(triphenylstannyl)stannylene (17b). The calculations suggest that 17b is formed via ultrafast rearrangement of a novel phenyl-bridged stannylidenestannylene intermediate (20), which can be formed either directly by "endo" dimerization of SnPh2 or by isomerization of the "exo" dimer, tetraphenyldistannene (16b); the predicted barriers for these rearrangements are consistent with the experimental finding that the observed product is formed at close to the diffusion-controlled rate. Absolute rate and equilibrium constants are reported for the reactions of SnMe2 and SnPh2 with Me2SnCl2 and methanol (MeOH), respectively, in hexanes at 25 °C.
- Duffy, Ian R.,Leigh, William J.
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p. 5029 - 5044
(2015/11/09)
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- Transfer of organic groups to gold using organotin compounds
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PhSnMe3 undergoes transmetallation with [AuCl(EPh3)] (E = P, As) in refluxing toluene forming [AuPh(EPh3)] and Me 3SnCl. The analogous nBu derivative does not transmetallate, even under forcing conditions. Similarly, 1-(trimethylstannyl) naphthalene and 1-(trimethylstannyl)-8-iodonaphthalene react with [AuCl(PPh 3)] to give good yields of the corresponding naphthylgold(I) complexes which were spectroscopically and structurally characterised.
- Meyer, Nadine,Sivanathan, Sivatharushan,Mohr, Fabian
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p. 1244 - 1247
(2011/04/22)
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- A unique Pd4 platform with CH3 and μ-CH 2 groups and its C-C coupling reaction with simple olefins
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(Chemical Equation Presented) Menage a quatre: The Pd 4 complex 1 features both terminal CH3 and bridging CH2 groups, and it reacts with ethylene at room temperature to give mainly propene. NMR spectroscopic studies reveal several intermediates in the formation of 1 from Pd2 building blocks.
- Sachse, Anna,John, Michael,Meyer, Franc
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p. 1986 - 1989
(2010/06/19)
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- A sterically congested aryltrimethylstannane - Synthesis, reactivity, transmetalation and CH-π interaction
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The synthesis of a novel sterically congested tetraorganotin compound, (4-tert-butyl-2,6-dimesitylphenyl)trimethylstannane (1), is reported and its reactivity with special focus on transmetalation studied. The reaction of compound 1 with reagents such as HgCl2, BiCl3 and HOTf gave (4-tert-butyl-2,6-dimesitylphenyl)dimethyltin chloride (2) and (4-tert-butyl-2,6-dimesitylphenyl)dimethyltin triflate (3), respectively, as a result of selective tin-methyl bond cleavage. Less bulky aryltrimethyltin derivatives react with BiCl3 to give both tin-methyl and tin-aryl bond cleavage. Hydrolysis of compound 3 proceeds slowly to give bis-(4-tert-butyl-2,6-dimesitylphenyl)dimethyl stannoxane (5) via the intermediate (4-tert-butyl-2,6-dimesitylphenyl)dimethyltin hydroxide (4). All terphenyldimethyltin derivatives that were characterized by single crystal X-ray diffraction analysis show C-H?π interactions. Based on these results, the optimum C-H?π distance (C?centroidaryl distance) is suggested to be in the range 3.4 and 3.5 A?.
- Mehring, Michael,Nolde, Christof,Schürmann, Markus
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p. 745 - 752
(2009/05/30)
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- Synthesis of ethyl 4-chloro-2-oxobut-3-ynoate and its addition to alkyl vinyl ethers
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Ethyl 4-chloro-2-oxobut-3-ynoate has been synthesized for the first time and its addition to alkyl vinyl ethers of various structures has been studied.
- Koldobskii,Solodova,Godovikov,Kalinin
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p. 1568 - 1570
(2009/09/30)
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- 1,1,2,2-tetramethyl-1,2-bis(phenylthiomethyl)disilane, a flexible ligand for the construction of macrocyclic, mesocyclic, and bridged dithioether complexes. Synthesis of the bis-silylated olefins Z-(PhSCH2)Me 2SiC(H)=C(Ar)SiMe2(CH2SPh) by catalytic activation of the Si-Si bond
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The functionalized disilane (PhSCH2)Me2SiSiMe 2(CH2SPh) (1) has been prepared and coordinated as a dithioether ligand on [PtCl2(PhCN)2] to afford the fluxional seven-membered chelate complex cis-[PtCl2{(PhSCH 2)2Si2Me4}] (2a). After metathesis reaction of 2a with NaI the diiodo derivative cis-[PtI2{(PhSCH 2)2Si2Me4}] (2b) was obtained. Treatment of [Re(μ-Br)(CO)3THF]2 with 1 equiv of 1 yields the bromo-bridged dinuclear complex fac-[{Re(μ-Br)(CO) 3}2{μ-(PhSCH2)2Si 2Me4}] (5), which is spanned by 1 forming a 10-membered mesocycle. Addition of a further equivalent of 1 yields the dinuclear macrocyclic compound fac-[{ReBr(CO)3}2{μ-(PhSCH 2)2Si2Me4}2] (4), forming a 14-membered ring system. The chloro-bridge of [RuCI(μ-Cl)(CO) 3]2 is cleaved by 1 to give the dinuclear compound fac-[{RuCl2(CO)3}2{μ-(PhSCH 2)2Si2Me4}] (6), in which the two metal fragments are linked by the thioether functions. In the presence of catalytic amounts of Pd(OAc)2/CNR, the Si-Si bond of 1 is cleaved and addition across the triple bond of phenylacetylene or p-tolylacetylene affords the bis-silylated olefins Z-(PhSCH2)Me2SiC(H)=C(Ar) SiMe2(CH2SPh) (7a Ar = Ph; 7b Ar = p-Tol). The new compounds have been studied by multinuclear NMR techniques; the crystal structures of 2a, 2b, 4, 5, 6, and 7a have been determined by X-ray diffraction studies.
- Peindy, Harmel N.,Guyon, Fabrice,Jourdain, Isabelle,Knorr, Michael,Schildbach, Daniel,Strohmann, Carsten
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p. 1472 - 1479
(2008/10/09)
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- Substituent-control of two modes of intramolecular reactions of allyloxy-silyllithiums and propargyloxy-silyllithiums
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Intramolecular reactions of the [(allyloxy)silyl]lithiums and the [(propargyloxy)silyl]lithiums have been investigated. The [(allyloxy)silyl] lithiums proceed in two reaction modes depending on the electronic effect of the substituents at the terminus of the olefin. The [(allyloxy)silyl]lithiums bearing hydrogen, n-C6H13, or trimethylsilyl substituent undergo the [2,3]-sila-Wittig rearrangement to afford the lithium allylsilanolates, while those bearing the phenyl, thienyl, or triphenylsilyl substituent experience the 4-exo-trig cyclization and subsequent 1,3-cycloelimination to give the lithium cyclopropylsilanolates. On the other hand, the [(propargyloxy)silyl]lithiums preferentially undergo the 4-exo-dig cyclization over the [2,3]-sila-Wittig rearrangement in all cases.
- Kawachi, Atsushi,Maeda, Hirofumi,Tamao, Kohei
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p. 1520 - 1527
(2007/10/03)
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- A catalytic and mechanistic investigation of a PCP pincer palladium complex in the Stille reaction
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In an improved procedure, the complex {2,6-bis[(diphenylphosphino)methyl] benzene}chloropalladium(II) (1) was synthesised as its THF adduct and the structure was determined by X-ray crystallography. The catalytic properties of the derivative {2,6-bis[(diphenylphosphino)methyl]benzene}(trmuoroacetato) palladium(II) (2) was investigated in the Stille reaction. Complex 2 proves to be an excellent catalyst for the C-C cross-coupling between trimethyl phenyl stannane and aryl bromides using a very low catalyst loading (0.1-0.0001%), giving high turnover numbers (TONs) up to 6.9 × 105. A kinetic investigation of the catalytic reaction suggests a heterogeneous colloidal palladium catalyst formed from the PCP Pd(II) pre-catalyst. The Royal Society of Chemistry 2005.
- Olsson, Daniel,Nilsson, Patrik,El Masnaouy, Mostafa,Wendt, Ola F.
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p. 1924 - 1929
(2007/10/03)
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- PROCESS FOR THE PREPARATION OF HYDROCARBYL HALIDES
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Described is a process for the preparation of hydrocarbyl metal halides, such as alkyl tin chlorides, in which a reaction between the metal in its metallic state and a hydrocarbyl halide is catalyzed by a dihydrocarbyl sulfoxide or a dihydrocarbyl formamide in the presence of a hydrocarbyl metal halide and wherein the pressure of the reaction vessel is varied during the reaction.
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Page/Page column 12
(2008/06/13)
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- Reactivity of silyl-substituted Allyl compounds with group 4, 5, 9, and 10 metals: Routes to η3-allyls, alkylidenes, and sec-alkyl carbocations
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Whereas the reaction of alkali-metal salts of silyl-allyls E +[C3H3(SiMe3)2-1,3] - (E = Li, K) with group 4 and group 5 metal halides gave intractable reduction products, Co(acac)3 and Ni(acac)2 reacted with K[C3H3(SiMe3)2-1,3] to give Co{eta;3-C3H3(SiMe3) 2-1,3}2 (1) and Ni{η3-C3H 3(SiMe3)2-1,3}2 (2), respectively. The reaction of K[C3H3(SiMe3)2-1,3] with Me3SnCl afforded Me3SiCH=CHCH(SiMe 3)(SnMe3) (3), which reacted cleanly with TaCl5 to give [η3C3H3(SiMe3) 2-1,3}TaCl4 (4). Treatment of this complex with tetramethylethylenediamine led to HCl abstraction, and the allyl complex was transformed into the vinyl-alkylidene compound Me3SiCH=CHC(SiMe 3)=TaCl3(TMEDA) (5). Whereas in the case of TaCl 5 dehalostannylation was facile, the reaction of 3 with ZrCl 4 and HfCl4 took a different course, leading instead to the addition of Me3Sn+ to 3 to give [HC{CH(SiMe 3)(SnMe3)}2]+[M2Cl 9]- (6, M = Zr; 7, M = Hf), the first examples of isolable sec-alkyl carbocations. These salts are surprisingly thermally stable and melt > 100°C; this stability is largely due to delocalization of the positive charge over the two tin atoms. The crystal structures of 1, 2, and 5-7 are reported.
- Schormann, Mark,Garratt, Shaun,Bochmann, Manfred
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p. 1718 - 1724
(2008/10/09)
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- Novel synthesis of zirconocene difluoride and alkyl monofluoride complexes
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Starting from zirconocene bis(trimethylsilyl)acetylene complexes Cp′2Zr(L)(η2btmsa) via the 2-vinylpyridine complexes Cp′2Zr(2-vipy) a novel synthetic method for zirconocene difluoride and alkyl monofluoride complexes was elaborated. Examples with selected different ligand systems Cp′2 [Cp2 = bis(η5-cyclopentadienyl); ebthi = 1,2-ethylene-1,1′- bis(η5-tetrahydroindenyl); (thi)2 = bis(η5-tetrahydroindenyl); Me2Si(η5- C5H4)2 = dimethylsilylbis-(η5- cyclopentadienyl); (i)2 = bis(η5-indenyl); ebi = 1,2-ethylene-1,1′-bis(η5-indenyl); and Me 2Si(η5-C9H10)2 = dimethylsilyl-1,1′-bis(η5-tetrahydroindenyl)] were synthesized. In the series of these investigations new complexes (i) 2Zr(THF)(η2-btmsa) (1), rac-(ebi)Zr(THF) (η2-btmsa) (2), (thi)2Zr(2-vipy) (3), Me 2Si(η5-C5H4)2Zr(2- vipy) (4), (i)2Zr(2-vipy) (5), and rac-(ebthi)-Zr(2-Ph-vipy) (6) were prepared as starting materials. Different methods for preparation of the zirconocene difluorides rac-(ebthi)ZrF2 (7), (thi) 2ZrF2 (8), Me4C2(η5- C5H4)2ZrF2 (9), and Me 2Si(η5-C9H10) 2ZrF2 (10) and the monofluorides Cp2Zr(F) (CH2CH2-2-Py) (11), rac-(ebthi)-Zr(F)(CH 2CH2-2-Py) (12), (thi)2Zr(F)(CH 2CH2-2-py) (13), Me2Si(η5-C 5H4)2Zr(F)(CH2CH2-2-py) (14), and Me2Si(η5-C9H10) 2ZrF(Me) (15) are reported and compared. The molecular structures of the bis-η5-tetrahydroindenyl complexes 3, 8, and 13 were confirmed by X-ray crystal structure analysis.
- Spannenberg, Anke,Arndt, Perdita,Baumann, Wolfgang,Burlakov, Vladimir V.,Rosenthal, Uwe,Becke, Sigurd,Weiss, Thomas
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p. 3819 - 3825
(2008/10/09)
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- CATALYSTS WITH A DONOR-ACCEPTOR INTERACTION
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The present invention relates to compounds in which a transition metal is complexed with two ligand systems and the two systems are reversibly bonded together by at least one bridge consisting of a donor and an acceptor, at least one substituent on the acceptor group being a fluorinated aryl radical, to the use of these compounds as catalysts and to a process for the polymerization of olefins.
- -
-
Page column 22-23
(2010/02/05)
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- Configurational selectivity in benzyldimethylarsine complexes of palladium(II) and platinum(II): Synthesis, spectroscopy and structures
-
Benzyldimethylarsine complexes of palladium(II) and platinum(II) with the formulae [MX2(BzAsMe2)2] (X=Cl, Br, I), [M2Cl2(μ-Cl)2(BzAsMe2) 2], [Pd2Cl2(μ-OAc)2(BzAsMe2) 2], [Pd2Me2(μ-Cl)2(BzAsMe2) 2] and [Pd2X2(μ-N^N)2(BzAsMe 2)2] (M=Pd or Pt; N^N=pyrazolate (pz) or 3,5-dimethylpyrazolate (dmpz)) have been prepared. All complexes have been characterised by elemental analysis, IR, UV-Vis absorption and NMR (1H, 13C, 195Pt) spectroscopy. The molecular structures of the complexes [MX2(BzAsMe2)2] (M=Pt or Pd; X=Cl, Br or I) have been established by NMR spectroscopy and single crystal X-ray diffraction analysis and reveal a clear dichotomy in solution and in the solid between the compounds with X=Cl in a cis configuration and the trans configured bromide and iodide complexes.
- Phadnis, Prasad P.,Jain, Vimal K.,Klein, Axel,Weber, Michael,Kaim, Wolfgang
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p. 119 - 128
(2008/10/08)
-
- Synthesis and reactivity of cyclopentadienyl and indenyl ligands bearing ω-fluorinated pendant groups. Crystal structure of (ortho-F-C6H4)-CPh2-C5H 4SiMe3
-
A series of cyclopentadienes and indenes with ω-fluorinated pendant groups have been synthesised and their reactivity towards metallating agents n-BuLi, NaH, TIOEt, Me3SiCl, Me3SnCl, TiHal4, ZrX4 (X = Cl, NMe2) has been investigated. The crystal structure of 1-trimethylsilyl-3-(diphenyl-ortho-fluorophenyl-methyl)-cyclopentadiene (3) was determined.
- Khvorost,Lemenovskii,Ustynyuk,Rufanov,Kipke
-
p. 1207 - 1214
(2007/10/03)
-
- Mixed metal acetylides: The Pt(II) aryl acetylide '[PtC6H2(CH2NMe2)2-2,6-(C≡C)-4]' as a connective fragment
-
Using Me3SiC≡C{Pt}Cl (1; Me3SiC≡C{Pt} = [Pt(C6H2- {CH2NMe2}2-2,6-{C≡CSiMe3}-4]+) a series of platinum monoacetylides of the type XC≡C{Pt}C≡CR [X = SiMe3: 2, R = Ph; 3, R = (η5- C5H4)Fe(η5-C5H5) (abbreviated as Fc); 4, R = C6H4CN-4; 5, R = C6H4(C≡CSnMe3)-4; X = H: 7, R = Ph; 8, R = Fc; 9, R = C6H4CN-4] have been prepared. Studies directed towards the coordinative properties of the C2 unit of 1 have been carried out and heterotrimetallic [μ(Me3SiC≡C{Pt}Cl][Co2(CO)6] (10) could be synthesised. The successful attachment of 1 to a Ph3PAu unit leads to linear PhaPAuC≡C{Pt}Cl (11). Treatment of 11 with FcC≡CSnMe3 produces the heterotrimetallic rigid-rod shaped complex Ph3PAuC≡C{Pt}C≡CFc (13). Cyclic voltammetric studies carried out on these Ph3PAu-capped molecules show that the attachment of an organometallic entity on either side of the C≡C{Pt} fragment leads to a facilitation of the Pt(II)/Pt(IV) oxidation.
- Back,Gossage,Lang,Van Koten
-
p. 1457 - 1464
(2007/10/03)
-
- Reactions of S-trimethylstannyl and S-(3-trimethylstannylpropyl) derivatives of 1,5-pentanedithiol with N,4-dichlorobenzenesulfonamide sodium salt
-
Difunctional derivatives of 1,5-pentanedithiol, 1,5-bis(trimethylstannylthio)pentane(CH2)5(SSnR 3)2 and 1,5-bis(3-trimethylstannylpropylthio)pentane (CH2)5[S(CH2)3SnR3] 2 (R = Me), differ by mutual arrangement of the tin and sulfur atoms and therefore react differently with N,4-dichlorobenzenesulfonamide sodium salt ArSO2N(Na)Cl (Ar = 4-ClC6H4). The first of these substrates possesses two direct Sn-S bonds which are cleaved by the action of 2 equiv of 4-ClC6H4SO2N(Na)Cl (desulfurization). The resulting pentamethylene-dithiobis-sulfonamide (CH2)5[SN(SnMe3)SO2Ar]2 undergoes oxidative imination of both S(II) atoms with additional 2 equiv of 4-ClC6H4SO2N(Na)Cl to afford sulfinimidamide derivative (CH2)5[S(=NSO2Ar)-N(SnR3)SO 2Ar]2. By contrast, both pairs of the sulfur and tin atoms in the bissulfide (CH2)5[S(CH2)3SnR3] 2 are separated by a trimethylene bridge, and this substrate reacts with 2 equiv of 4-ClC6H4SO2N(Na)Cl to form tin-containing bis-sulfimide (CH2)5[S(=NSO2Ar)(CH2) 3SnR3]2. According to the 1H and 13C NMR data, interaction between two pairs of the tin and sulfur atoms at both ends of the bis-sulfimide molecule gives rise to independent sterically favorable coordination rings.
- Shcherbakov,Grigor'eva,Kurskii
-
p. 902 - 906
(2007/10/03)
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- Zirconocenes and hafnocenes with boron-substituted cyclopentadienyl-ligands and the method of producing them
-
Zirconocenes and hafnocenes with borylated cyclopentadienyl ligands and methods for the preparation thereof.
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-
- Synthesis and reactivity of stannyloligosilanes, I. Stannyloligosilane chains containing SiMe2 moieties
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Stannyloligosilanes 1 and 2 with terminal organotin groups are available by reacting alkali metal tri-or diorganostannides with α,ω-dichloro-or difluorosilanes, or by treatment of organochlorostannanes with α,ω-difluorosilanes in the presence of magnesium. Attempts to functionalize the triorganotin derivatives 2 by halogenation reagents did not result in the halogen compounds 5; instead cleavage of silicon-tin bonds is observed. In contrast, reactions of the hydridotin derivatives 1 with CHX3 (X = Cl, Br) lead to the quantitative formation of the bis(chloro-or bromostannyl)oligosilanes 5. All compounds were characterized by NMR, IR, MS and elemental analysis. In addition, the triorganotin compound 2i and the hydridotin species 1b have been characterized by X-ray crystallography.
- Uhlig, Frank,Kayser, Christian,Klassen, Ralph,Hermann, Uwe,Brecker, Lothar,Schürmann, Markus,Ruhland-Senge, Karin,Englich, Ulrich
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p. 278 - 287
(2007/10/03)
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- Synthesis of Boron-Halogenated Diborylamines and Diborylhydrazines by Cleavage of Stannazanes
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The diborylamines R'-N(BRX)2 (3; X=Cl, Br) are obtained by stannazane cleavage of distannylorganylamines R'-N(SnMe3)2 (4) with alkyldihaloboranes RBX2 in a 1:2 molar ratio. The presence of the sterically demanding substituents R and R' also causes carbon-tin bond cleavage, resulting in low yields of 3. However, carbon-tin bond cleavage can be suppressed by the use of bis(dimethylchlorostannyl)organylamines 5 as the nitrogen source for the synthesis of diborylamines. This results in almost quantitative yields of the compounds 3. Treatment of the distannylhydrazines R2N-N(SnMe3)2 (7) with RBX2 in a 1:2 molar ratio leads to the formation of N,N-bis(alkylhaloboryl)hydrazines 8 under mild conditions and in good yield. The molecular structures of 3 and 8 were determined by multinuclear magnetic resonance spectra in solution as well as by X-ray structure analysis in the case of 8d. A typical structural feature of 8d is the intramolecular BN adduct formation. Support for the constitutions of compounds 8c comes from MS fragmentation patterns as well as from IR spectra.
- Diemer, Stefan,Noeth, Heinrich,Storch, Wolfgang
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p. 1765 - 1780
(2007/10/03)
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- Intermediates and products of the hexachlorodisilane cleavage of group 14 element phosphanes and amines - Molecular structure of di-tert- butyl(trichlorosilyl)phosphane in the gas phase determined by electron diffraction and ab Initio calculations
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Reactions of dialkyl(trimethylsilyl)phosphanes RR'PSiMe3 (1: R, R' = tBu; 3: R, R' = iPr; 5: R = iPr, R' = tBu) with Si2Cl6 provide stable trichlorosilylphosphanes RR'PSiCl3 (2, 4, 6); the reactions of silyl- and stannylamines of iPr2NMMe3 (M = Si: 11; M = Sn: 12) with Si2Cl6, however, provide the stable pentachlorodisilanylamine iPr2NSi2Cl5 (13). Heating of 1 with the technical mixture Me2(Cl)SiSiCl2Me/(MeCl2Si)2 yields the stable silylphosphane tBu2PSiMe2Cl (8) and the disilanylphosphane tBu2PSi(Me)(Cl)Si(Me)Cl2 (9). Methylation of 9 with MeLi gave tBu2PSi2Me5 10, which was isolated in a pure state. Reactions of tBu(iPr)PSiMe3 (5) and of organometal phosphanes tBu(iPr)PMR3 (14: M = Ge, R = Me; 17a-c: M = Sn; R = Me, Et, nBu) with Si2Cl6 were monitored by 31P, 29Si, and 119Sn NMR. - In the first step of these reactions, new tBu(iPr)PSi2Cl5 (7) is formed. 7 is accompanied by increasing amounts of tBu(iPr)PSiCl3 (6) and Me3GeSiCl3 (15)/(Me3Ge)2Si(SiCl3)2 (16) or traces of compounds R3SnSiCl3 (19a-c) that decompose providing (R3Sn)2Si(SiCl3)2 (18a-c) and nBu3SnSi(SiCl3)3 (20c). Subsequently, compounds 19a-c decompose providing increasing amounts of 18a-c. Stannylphosphane 17b is also cleaved by SiCl4 leading to 6 with liberation of Et3SnCl, whereas 17b is formed from the reaction of 5 with Et3SnCl under liberation of Me3SiCl. The suggestion of an extra stabilisation of P-Si bonds of trichlorosilylphosphanes was subjected to direct evidence through the structure determination of the trichlorosilylphosphane tBu2PSiCl3 (2) in the gas phase by electron diffraction. This crowded molecule has a 'normal' P-Si bond length of 225.0(12) pm; its C1 symmetric conformation with both tBu groups and the SiCl3 group twisted about 17°from the perfectly staggered positions, and with each of the three groups tilted about 6°away from each other, allows to reduce steric strain.
- Du Mont, Wolf-W.,Müller, Lars,Martens, Reiner,Papathomas, Paul M.,Smart, Bruce A.,Robertson, Heather E.,Rankin, David W. H.
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p. 1381 - 1392
(2007/10/03)
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- Trichlorosilylation of chlorogermanes and chlorostannanes with HSiCl3/Net3 followed by base-catalysed formation of (Me3Ge)2Si(SiCl3)2 and related branched stannylsilanes
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Chlorotrimethylgermane 1 and dichlorodimethylgermane 4 react with trichlorosilane and triethylamine to provide trichlorosilylgermanes Me4-nGe(SiCl3)n (n = 1: 2; n = 2: 5) in fair yields, as distillable liquids. The formation of 2 is followed by base-catalysed decomposition reactions leading to novel solid (Me3Ge)2Si(SiCl3)2 3. Chlorotrialkylstannanes 6a-c (6a: R = CH3, 6b: R = C2H5, 6c: R = n-C4H9) react with trichlorosilane and triethylamine providing the branched silylstannanes (R3Sn)2Si(SiCl3)2 7a-c and traces of silylstannanes R3SnSiCl3 8a-c. Only 7a was isolated in a pure state. Heating 7a or crude 7b and 7c with benzyl chloride leads to the formation of benzyltrichlorosilane (10). The constitution of compounds 2, 3, 5 and 7a was confirmed by MS, NMR and analytical data. The structures of C6D6-solvated 3 and C6H6-solvated 7a were determined by X-ray diffraction, and shown to be isotypic.
- Mueller, Lars,Du Mont, Wolf-Walther,Ruthe, Frank,Jones, Peter G.,Marsmann, Heinrich C.
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p. 156 - 163
(2007/10/03)
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- Borabenzene derivatives. 30. Bis(1-methylboratabenzene) compounds of Germanium, Tin, and Lead. First structural characterization of facial bonding of a boratabenzene to a p-element and the structures of Pb(C5H5BMe)2 and its 2,2′-bipyridine adduct
-
Bis(1-methylboratabenzene)lead, Pb(C5H5BMe)2 (1), was synthesized by the reaction of Li(C5H5BMe) with PbCl2 as a low-melting (mp 60°C) thermochromic yellow crystalline solid (63%). The lighter homologues Sn(C5H5BMe)2 (2) and Ge(C5H5BMe)2 (3) were obtained from 1-methyl-2-(trimethylstannyl)-1,2-dihydroborinine, 2-(Me3Sn)C5H5BMe, and SnCl2 and GeI2, respectively, as colorless liquids (70%). The plumbocene analogue 1 possesses a monomeric bent-sandwich structure with a bending angle of 135.2(3)°. Compound 1 forms addition compounds with nitrogen bases such as 1-TMEDA (6) and 1·bipy (7). Adduct 7 has a bent-sandwich structure with the 2,2′-bipyridine ligand in the pseudoequatorial plane; the bending angle is 139.1(5)°.
- Herberich, Gerhard E.,Zheng, Xiaolai,Rosenpl?nter, J?rg,Englert, Ulli
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p. 4747 - 4752
(2008/10/08)
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- Reaction of pentafluorophenylsulfenyl chloride with β-substituted trimethylstannylacetylene
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Unlike trimethylstannylacetylene, its β-substituted derivatives react with pentafluorophenylsulfenyl chloride with formation of acetylenic sulfides. The 19F NMR spectral parameters of pentafluorophenylthio-acetylenes show some correlations similar to those found for pentafluorophenyl-containing acetylenes.
- Bogoradovskii,Maksimov,Zubova
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p. 913 - 916
(2007/10/03)
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- Novel organoborane Lewis acids via selective boron-tin exchange processes - Steric constraints to electrophilic initiation by the boron halide
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With the purpose of preparing novel mono- and bidentate organoboron Lewis acids, the scope and limitations of synthesizing the requisite organoboranes by the boron-tin exchange between a boron halide and the appropriate organostannane have been examined in detail. The following organotin derivatives have been obtained either from the corresponding RMgBr or RLi reagent and MenSnCl4-n or from a Barbier procedure using the organic halide, Me3SnCl and magnesium metal: 1,2-bis(trimethylstannyl)ethyne, o-, m-, and p-bis(trimethylstannyl)benzenes, α,o-bis(trimethylstannyl)toluene, α,α-bis(trimethylstannyl)-o-xylene, and 2,2-dimethyl-2-stannaindane. The individual interaction of the 1,2-bis(trimethylstannyl)ethyne and the isomeric bis(trimethylstannyl)benzenes with Et2BBr produced the corresponding bis(diethylboryl)-derivatives. By contrast, with Et2BCl the α,o-bis(trimethylstannyl)toluene gave only o-diethylboryl-α-trimethylstannyltoluene and with BCl3 the α,α′-bis(trimethylstannyl)-o-xylene formed only α,α′-bis-(chlorodimethylstannyl)-o-xylene. Furthermore, in the attempted double boron-tin exchange between o-bis(trimethylstannyl)benzene and BCl3, an unprecedented rearrangement of the 1-(dichloroboryl)-2-(trimethylstannyl)benzene intermediate into its 1-[chloro(methyl)boryl]-2-(chlorodimethylstannyl) isomer was observed. Likewise, o-bis(trimethylstannyl)benzene with PhBCl2 produced by a similar rearrangement 1-[methyl(phenyl)boryl]-2-(chloro-dimethylstannyl)benzene. The thermolysis of such boranes led variously to definite dimers or ill-defined oligomers. Preliminary studies of the properties of these organoboranes have identified the heightened Lewis acidity of 1,2-bis(diethylboryl)ethyne and the π-electron delocalization involving the 2pΖ-boron orbitals in the 9,10-dihydro-9,10-diboraanthracene system. Finally, an electronic mechanism for the boron-tin exchange has been developed to account for the selectivity of the boron halide's attack at unsaturated carbon-tin bonds.
- Eisch, John J.,Kotowicz, Boguslaw W.
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p. 761 - 769
(2007/10/03)
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- Thermal decomposition of platinum(IV)-silicon, -germanium, and -tin complexes
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The thermal decomposition of a number of complexes of the type [PtMe2(Me3E)X(diimine)] (E = Si, Ge, Sn; X = Cl, Br, I) has been studied. The thermal stability of complexes, as determined by thermogravimetric analysis (TGA), varies depending on the diimine ligand in the order 2,2′-bipyridyl (bpy) > 4,4′-di-tert-butyl-2,2′-bipyridyl (bpy-tbu2) > N-(2-(dimethylamino)ethyl)pyridine-2-aldimine (paen-me2) > (2-imino-n-propyl)pyridine (py-n-pr). Stability also varies according to the trends E = Sn ≈ Ge > Si and X = I > Br > Cl. The products of thermal decomposition have also been determined by 1H NMR and three distinct modes of decomposition are evident: reductive elimination of Me3EX, reductive elimination of Me4E, and α-elimination of Me2E. The competition between reductive elimination of Me3EX and Me4E depends primarily on the halide, X, with the ratio Me3EX:Me4E highest for X = Cl and lowest for X = I. The competition between reductive elimination and α-elimination depends primarily on E, with the tendency to α-elimination of Me2E increasing as E = Si 2(Me3Si)(bpy)] as 233 ± 14 kJ mol-1.
- Levy, Christopher J.,Puddephatt, Richard J.
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p. 4115 - 4120
(2008/10/08)
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- Preparation of oligosilanes containing perhalogenated silyl groups (-SiX3, -SiX2-, >SiX-, X = Cl, Br) and their hydrogenation by stannanes
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Starting from methylphenylsubstituted oligosilanes the disilanes SiX3-SiXi,Me3-i (i = 0, 1, 2; X = Cl, Br), trisilanes SiX2(SiXiMe3-i) (i = 0, 1) and branched tetrasilanes SiX(SiXMe2)3 were synthesized and their behavior towards the Lewis-base catalyzed hydrogenation by stannanes was investigated. In the case of methylchlorodisilanes SiCl3-SiCliMe3-i Si-Si bond cleavage competes with the hydrogenation reaction.
- Herzog,Roewer
-
p. 217 - 223
(2007/10/03)
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- Synthesis and structure of tris(trialkylstannyl)- and tris(dialkylhalostannyl)amines; of the Sn3N by Sn-X-Sn
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Tris(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(diorganylhalostannyijamines (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 Br3Sri3N skeleton and SnN bond lengths of 1.99 A, which beside those of 3a are the shortest found so far. According to MNDO approximate and ab initia calculations it interactions between the lone electron pair at the N atom and empty orbitals at the Sn atoms can be excluded. Therefore, the tristannylamines 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. VCH Verlagsgesellschaft mbH 1996.
- Appel, Andrea,Kober, Christian,Neumann, Christine,Noeth, Heinrich,Schmidt, Martin,Storch, Wolfgang
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p. 175 - 189
(2007/10/02)
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- Template-driven syntheses of polymeric metal cyanides: A chiral nanoporous host for the nBu4N+ ion
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A comfortable fit is provided for the large tetrabutylammonium ion within the wide channels of the new host guest compound [(nBu4N)0.5(Me3Sn)3.5Fe(CN)6]. The lipophilic walls are formed by helical [Fe-CN-Sn-NC], chains involving [Fe(CNnMe3)6] octahedra that are enantiomorphically derivatized due to cross-linking.
- Schwarz,Eller,Siebel,Soliman,Fischer,Apperley,Davies,Harris
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p. 1525 - 1527
(2008/10/09)
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- Contributions to the chemistry of phosphorus, 238 [1] synthesis and properties of the phosphinocyclotriphosphane (t-BuP)2P-P(SnMe3)2
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The new phosphinocyclotriphosphane (t-BuP)2P-P(SnMe3)2 (1) has been obtained by reaction of di-tert-butylchlorocyclotriphosphane with tris(trimethylstannyl)phosphane, and has been isolated in pure form. The yellow solid is stable below 0°C under inert conditions. Compound 1 is a dynamic molecule, as the P atom of the [bis(trimethylstannyl)phosphino] group has a very low barrier to inversion due to the bulky and electropositive Me3Sn substituents.
- Baudler, Marianne,De Riese-Meyer, Loert
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p. 101 - 106
(2007/10/03)
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- Unsymmetrical Organotin Compounds in the Synthesis of Lanthanide Derivatives
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Transmetalation of lanthanide salts and Grignard-like organic lanthanide derivatives with mixed alkyl(vinyl)-aromatic organotin compounds was studied, and the possibility of synthesizing organolanthanide compounds through organotin derivatives was shown. The method is especiallly suitable for preparation of derivatives containing unsaturated groups.
- Rybakova,Starostina,Syutkina,Petrov
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p. 575 - 577
(2007/10/03)
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- Exploration of the Stille coupling reaction for the syntheses of functional polymers
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The palladium-catalyzed Stille coupling reaction was used for preparing functionalized, conjugated polymers. This reaction has several advantages, two of which are that it requires mild reaction conditions and produces high yields. Several factors which affect the polymerization processes were investigated, such as the catalyst composition and concentration, different solvents and ligands, and structures of monomers. It was found that solvents that could keep the macromolecules in solution and stabilize the palladium(0) catalyst would yield polymers with high molecular weights. If a Pd(II) compound was used as the catalyst, a stoichiometric adjustment of the distannyl monomer was necessary to enhance the molecular weight of the resulting polymer. In general, it was found that a combination of an electron-rich distannyl monomer and an electron-deficient dihalide (ditriflate) monomer forms polymers with relatively high molecular weights. To further demonstrate the versatility of the Stille reaction for polycondensations, different types of conjugated polymers with different properties and applications, such as liquid crystalline conjugated polymers and conjugated photorefractive polymers, were synthesized.
- Bao, Zhenan,Chan, Wai Kin,Yu, Luping
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p. 12426 - 12435
(2007/10/03)
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- Tin/mercury exchange in 1,2-distannyl-1-alkenes and 1-silyl-2-stannyl-1-alkenes
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1,2-Bis(chloromercuri)alkenes, 1-trimethylsilyl-2-chloromercuri-alkenes and 1-trimethylsilyl-2-organomercurialkenes can be readily made by transmetallation of the corresponding trimethyltin compounds with HgCl2 and RHgCl; their structures have been confirmed by multinuclear NMR data.The new compounds are expected to have a large synthetic potential involving lithium/mercury exchange, and subsequent reaction with electrophilic reagents.Key words: Mercury; Nuclear magnetic resonance; Tin; Silicon
- Mitchell, T. N.,Kowall, B.
-
-
- Some further studies on acyltrimethylstannanes
-
The scope and limitations of the palladium-catalysed preparation of acyltins from ditins and acyl chlorides are discussed in detail.Preliminary studies on the chemistry of acyltrimethylstannanes are described.
- Mitchell, Terence N.,Kwetkat, Klaus
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p. 127 - 138
(2007/10/02)
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- Haloalkylation process
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A process for the haloalkylation of certain tin, phosphorus and germanium halides is disclosed. The process is carried out typically in a halocarbon solvent at temperatures of less than 0° C. using as the haloalkylating reagent an admixture of a haloalkyl halide and tris(lower alkylamino)phosphine.
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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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