Silicon vs. carbon containing ions: 1,3-proton transfers within the (CH3)(X)Si(OR)(+OHR ') units

Abstract : In the cell of an FT-ICR spectrometer, (CH3)(X)C(OCR)(+OHR') and (CH3)(X)Si(OCR)+OHR' (R and R'=H, CH3 or C2H5; X=H or CH3) covalent ions were generated by reaction of the (CH3)(X)+Si-OCR' cations with water or alcohols. In the so-formed covalent ions, experiment shows that 1,3-H+ transfers from oxygen to oxygen are often easy in silicon containing ions while they are not observed in the corresponding ions containing only carbon. Calculations indicate that the energy required for a 1,3-H+ transfer from oxygen to oxygen is almost identical whether the transition state contains a silicon atom or not. The greater strength of the Si-O bond in cations, compared to that of the C-O bond or, in other words, the great electrophilic character of cations possessing a Si+, is the main factor explaining the difference in the behavior of the studied silicon containing ions and ions containing exclusively carbon.
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Submitted on : Friday, December 13, 2013 - 4:06:39 PM
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D Leblanc, Hristo Nedev, Henri Audier. Silicon vs. carbon containing ions: 1,3-proton transfers within the (CH3)(X)Si(OR)(+OHR ') units. International Journal of Mass Spectrometry, Elsevier, 2002, 219 (3), pp.537-547. ⟨10.1016/S1387-3806(02)00707-8⟩. ⟨hal-00918101⟩

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