| Autor: |
Byun J; Department of Chemistry, Washington University, St Louis, MO 63130, USA., Gross ML, George M, Parees DM, Kamzelski AZ, Swijter DF, Willcox DA |
| Jazyk: |
angličtina |
| Zdroj: |
Journal of mass spectrometry : JMS [J Mass Spectrom] 1997 Jan; Vol. 32 (1), pp. 71-80. |
| DOI: |
10.1002/(SICI)1096-9888(199701)32:1<71::AID-JMS452>3.0.CO;2-9 |
| Abstrakt: |
Two fragmentations of (CH3)3SiO-CR2-X-CR2-OSi(CH3)3, where X is a rigid group such as a triple bond or an aromatic ring, are losses of a methyl or R group (where R is H or alkyl). The metastable-ion dissociations of [M-R]+ and [M-CH3]+ ions include the rearrangement of a trimethylsilyl (TMS) cation and a (CH3)2Si = O neutral species through an ion-neutral complex. On the basis of tandem mass spectrometry (MS/MS), exact mass measurement and isotopic labeling experiments, it has been established that the two trimethylsilyloxy groups in the TMS ethers interact across a wide range of distances via an ion-neutral complex. The migration of a TMS cation occurs when the group that is bound to carbon is expelled as a radical by an oxygen-directed cleavage to give a trimethylsilylated oxonium ion. If, on the other hand, a methyl radical is lost from the silicon atom, then (CH3)2Si = O migrates. The mobilities of the TMS cation and the neutral (CH3)2Si = O are governed by the capability of the rigid group to delocalize charge. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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