21752-80-7Relevant academic research and scientific papers
Visiting the Limits between a Highly Strained 1-Zirconacyclobuta-2,3-diene and Chemically Robust Dizirconacyclooctatetraene
Rei?, Fabian,Rei?, Melanie,Spannenberg, Anke,Jiao, Haijun,Baumann, Wolfgang,Arndt, Perdita,Rosenthal, Uwe,Beweries, Torsten
, p. 5667 - 5674 (2018)
The reaction of the allene precursor Li2(Me3SiC3SiMe3) with [Cp2ZrCl2] (Cp=cyclopentadienyl) was examined. The selective formation of hitherto unknown linear, allene-bridged dizirconocene complexes [(Cp2ZrCl)2{?μ-(Me3Si)C3(SiMe3)?}] and [(Cp2Zr)2{?μ-(Me3Si)C3(SiMe3)?}2] was observed. Upon σ coordination of the allenediyl unit to {Cp2Zr}, pyrophoric Li2(Me3SiC3SiMe3) is tamed stepwise to yield a surprisingly robust 1,5-dizirconacyclooctatetra-2,3,6,7-ene with cumulated double bonds. This complex is unexpectedly inert against moisture, air, water and acetone. Surprisingly, it degrades under MS conditions to give the highly strained 1-zirconacyclobuta-2,3-diene. All compounds isolated have been fully characterised and the molecular structures are discussed. The stability and reactivity of these complexes are rationalised by DFT computations.
1-Titanacyclobuta-2,3-diene-an elusive four-membered cyclic allene
Rei?, Fabian,Rei?, Melanie,Bresien, Jonas,Spannenberg, Anke,Jiao, Haijun,Baumann, Wolfgang,Arndt, Perdita,Beweries, Torsten
, p. 5319 - 5325 (2019)
The synthesis of an unusual 1-metalla-2,3-cyclobutadiene complex [rac-(ebthi)Ti(Me3SiC3SiMe3)] (rac-ebthi = rac-1,2-ethylene-1,1′-bis(η5-tetrahydroindenyl)), a formal metallacyclic analogue of a non-existent four-membered 1,2-cyclobutadiene, is described. By variation of the cyclopentadienyl ligand of the titanocene precursor it was possible to stabilise this highly exotic compound which selectively reacts with ketones and aldehydes to yield enynes by oxygen transfer to titanium. Analysis of the bonding and electronic structure of the metallacycle shows that the complex is best described as an unusual antiferromagnetically coupled biradicaloid system, possessing a formal Ti(iii) centre coordinated with a monoanionic radical ligand.
Titanocene Silylpropyne Complexes: Promising Intermediates en route to a Four-Membered 1-Metallacyclobuta-2,3-diene?
Rei?, Fabian,Rei?, Melanie,Spannenberg, Anke,Jiao, Haijun,Hollmann, Dirk,Arndt, Perdita,Rosenthal, Uwe,Beweries, Torsten
, p. 14158 - 14162 (2017)
Coordination of the alkyl-substituted alkynes Me3SiC2CH2R (1: R=SiMe3; 2: R=N(SiMe3)2) to titanocene centres [Cp′2Ti] (Cp′=Cp, Cp*) yields stable alkyne complexes of the type Cp′2Ti(η2-Me3SiC2CH2R) (3: Cp′=Cp, R=SiMe3; 5: Cp′=Cp, R=N(SiMe3)2; 6: Cp′=Cp*, R=SiMe3) that are not prone to alkyne/allene isomerisation. When reacting alkyne 2 with Cp*2TiCl2 and Mg formation of the complex Cp*2Ti(III)(η3-Me3SiC2CH2) (7) which displays a propargylic unit coordinated to the TiIII centre takes place. All complexes were fully characterised, the molecular structures for 5, 6, and 7 are discussed.
HALODESTANNYLATION OF BIS-, TRIS-, AND TETRAKIS(TRIMETHYLSTANNYL)PROPADIENES
Bogoradovskii, E. T.,Zavgorodnii, V. S.,Liepin'sh, E. E.,Petrov, A. A.
, p. 1306 - 1310 (2007/10/02)
Unlike the halogenation of stannylpropadienes which proceeds with the formation of SE' reaction products, the chlorination and bromination of polystannylpropadienes does not proceed unequivocally, the products formed being the result of type SE' and SE reactions, as well as of acetylene-allene isomerization.The iodination of polystannylpropadienes proceeds with the formation of SE reaction products and can be used as a method of synthesis of pure polyiodo-substituted propadienes.
SYNTHESIS AND ELECTROPHILIC SUBSTITUTION REACTIONS OF 1,3-DISUBSTITUTED PROPYNES CONTAINING GROUP-IVB ELEMENTS
Bogoradovskii, E. T.,Zavgorodnii, V. S.,Liepin'sh, E. E.,Birgele, I. S.,Petrov, A. A.
, p. 1295 - 1306 (2007/10/02)
The reaction of trialkylstannyldialkylamines and trialkylstannylpropadienes produces 1,3-bis(trialkylstannyl)propynes in high yield. 1,3-Bistrialkylsilyl(germyl)propynes and also certain 1,3-bis(trialkylstannyl)propynes can be obtained by the organomagnesium method.During the bromination of 1,3-bis(trialkylsilyl)(trialkylgermyl)propynes, the E-CH2Csp bond is preferentially split.In contrast to these, 1,3-bis(trialkylstannyl)propynes may undergo a bromodestannylation reaction at the Sn-Csp bond with the formation of 1-bromo-3-trialkylstannyl-1-propynes. 1,3-Bis(trialkylstannyl)propynes react with halosilanes with the formation of acetylene compounds only, whereby the variation of the nature of the silane and the structure of stannylpropyne enables selective splitting of the Sn-Csp or Sn-CH2Csp bond.
The Synthesis of Some Carbohydrate-Derived Precursors to Tylonolide, the Aglycon of the Antibiotic Tylosin
Hughes, Andrew B.,Stick, Robert V.,Tilbrook, D. Matthew G.
, p. 1681 - 1695 (2007/10/02)
Treatment of methyl 2,3-anhydro-4,6-O-benzylidene-α-D-alloside with the anion derived from trimethyl(prop-1-ynyl)silane, allylmagnesium chloride or isobutenylmagnesium chloride introduces a three- or four-carbon substituent at C2 of the sugar.In each case
The Synthesis and Molecular Structure of Tetra(isopropyl)silane
Anderson, David G.,Rankin, David W. H.,Robertson, Heather E.,Frazao, Carlos M. F.,Schmidbaur, Hubert
, p. 2211 - 2218 (2007/10/02)
Tetra(isopropyl)silane has been prepared using literature methods, with the individual steps improved by changes in some of the experimental conditions.The key reagent 2-lithiopropene, which can now be obtained in good yields from 1-methacrylic acid via 1,2-dibromo-1-methylpropionic acid and 2-bromopropene by treatment of the latter with ultrasound-activated lithium metal, was shown to contain mono- and dilithiopropyne.The reaction with chlorotrimethylsilane led to the corresponding silylated derivatives, while with silicon tetrachloride tetra(isopropenyl)silane was obtained, which after purification is easily converted into the title compound by catalytic hydrogenation. - The gas phase molecular structure of 4Si has been determined by electron diffraction.The parameters could be successfully refined for a model of S4 symmetry.Bond distances Si-C, C-C, and C-H as well as bond angles Si-C-C and C-C-H show the steric compression of the four isopropyl substituents.Steric strain is minimized by twists of the methyl groups and the isopropyl groups away from the fully staggered conformations, but also by an increase of two of the C-Si-C angles as compared to the remaining four, which are decreased relative to the tetrahedral standard.The structure differs strongly (mainly in the twist angles) from that of the isoelectronic tetra(isopropyl)phosphonium cation in 4P(1+)(1-), but is very similar to those of tetra(cyclohexyl)silane and of tri(isopropyl)phosphonium isopropylide, where the pyramidal configuration of the ylidic carbon atoms leads to a pseudo homoleptic array of the substituents at phosphorus. - Key Words: Conformational analysis / Electron diffraction / Organosilanes / Silane, tetra(isopropyl)-
UNE VOIE D'ACCES RAPIDE ET PRATIQUE AU TETRAKIS(TRIMETHYLSILYL)-ALLENE ET AU BIS(TRIMETHYLSILYL)-1,3 PROPYNE
Bennetau, Bernard,Youhouvoulou N'Gabe, Denis,Dunogues, Jacques
, p. 3813 - 3816 (2007/10/02)
Complete silylation of hexachlorobenzene using the Me3SiCl/Li/THF reagent at 0oC quantitatively affords tetrakis(trimethylsilyl)allene.This last upon a double protodesilylation with F3CCOOH at 0o, leads to the quantitative formation of 1,3-bis(trimethylsilyl)propyne via the 1,3,3-tris(trimethylsilyl)propyne.
