Bond Cleavage in Small Functionalized Molecules

The introduction of a charge-localizing heteroatom into a molecule is accompanied by obvious changes in the appearance of the mass spectrum. Withdrawal of an electron upon El must not necessarily affect a o-bond, because the electron can be supplied from one of the free electron pairs of the heteroatom. 

In the El mass spectrum of iodomethane the molecular ion, CHj-I, is detected as the base peak at m/z 142 (Fig. 6.2). An important new feature of the spectrum is the peak at m/z 127 due to an [M-CHs] ion. This signal is due to T also formed by a process that can also be classified as a-bond cleavage. Here, a single electron 

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