4964-03-8Relevant articles and documents
Insight into cis-to-trans olefin isomerisation catalysed by group 4 and 6 cyclopentadienyl compounds
Chahboun, Ghaita,Petrisor, Cristina E.,Gomez-Bengoa, Enrique,Royo, Eva,Cuenca, Tomas
, p. 1514 - 1520 (2009)
Intramolecular isomerisation of the pendant allyl unit present in the model compound [MoH(eta;5-C5H4SiMe 2CH2CH=CH2)- (CO)3] reported before was investigated by DFT calculations.
Isomeric C5H11Si+ ions from the trimethylsilylation of acetylene: An experimental and theoretical study
Siehl, Hans-Ullrich,Brixner, Sandra,Coletti, Cecilia,Re, Nazzareno,Chiavarino, Barbara,Crestoni, Maria Elisa,De Petris, Alberto,Fornarini, Simonetta
, p. 58 - 66 (2013)
The gas phase offers a unique medium to conduct the electrophilic addition reaction of (CH3)3Si+ (trimethylsilylium ion) to acetylene. However, this deceptively simple reaction displays a remarkable dependence on the gas phase pressure, revealing the interplay of competitive pathways. In FT-ICR mass spectrometry at ca 10-8 mbar, the nascent (CH3)3Si+-acetylene complex undergoes a rearrangement process yielding the CH2C(CH3)Si(CH 3)2+ ion. This structure has been assigned on the basis of the ion-molecule reactivity displayed by the sampled C 5H11Si+ adducts, matching the one of the model ion obtained from 2-(trimethylsilyl)propene. Whereas the absolute values of kinetic rate constants could not discriminate between isomeric species, the branching ratios for competitive addition-elimination channels in the reaction with i-C3H7OH and t-C4H9OCH 3 were found to be diagnostic of different structures. The pathways leading from the (CH3)3Si+-acetylene complex primarily formed to the candidate C5H11Si+ isomers have been investigated by ab initio quantum chemical calculations at CCSD(T)/6-311 ++G(2d,2p)//B3LYP/6-311G(2d,p) level. The energy profiles show that the path to the CH2C(CH3)Si(CH3) 2+ isomer is associated to the lowest activation energy barrier, below the reactants energy level. The energy released in the (CH 3)3Si+-acetylene association process, remaining stored in the complex formed at low pressure, thus allows the isomerization to a species holding the positive charge on electropositive silicon. Interestingly, the most stable of the conceivable isomers, (E)-(CH3)CHCHSi(CH 3)2+, is not accessed because of an activation energy barrier protruding above the reactants energy level. The combined information of ion-molecule reactivity and ab initio calculations of potential isomers and rearrangement pathways has thus afforded a comprehensive view of the (CH3)3Si+ addition reaction to acetylene under various pressure regimes.
Catalytic Conversion of Allylic Esters to Corresponding Allylic Silanes with Hexamethyldisilane and Palladium(0) or Rhodium(I) Complexes
Urata, Hisao,Suzuki, Hiroharu,Moro-oka, Yoshihiko,Ikawa, Tsuneo
, p. 607 - 608 (2007/10/02)
Treatment of allylic esters (R1CH=CR2CH2OCOR3:R1=H,Ar;R2=H, alkyl; and R3=Me,Ph) with hexamethyldisilane in the presence of catalytic amounts of PdL4 (L=PPh3 or P(OPh)3) or RhCl(PPh3)3 gives the corresponding allylic silanes in the excellent yield.
