Electron parity fragments

The fragmentation of these radical cations without any rearrangement or without any cleavage of an even number of bonds such as occurs in rings necessarily leads to an even-electron, or closed shell, ion and to a neutral radical. The parity rules were discussed in Section 6.6. 

McLafferty [9] proposed classifying the reactions of even-electron ions that obey the parity rule (an even ion yields an even ion + neutral fragment) as follows ... 

More generally, further complications arise for angular momentum couplings when the fragments show electronic angular momentum, but the fundamental symmetry rules are not affected by this. Early examples for detailed correlations include triatomic systems, and another more recent example is the correlation for atom + linear molecule. While for such simple cases, and planar molecules in general, parity is... 

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