Example of problems in photo-initiated spin trapping

9 Examples of problems in photo-initiated spin trapping 

From the above, it is evident that every photochemical system must be carefully analysed in order to establish the nature of the process of spin adduct formation. Not all systems have the inbuilt diagnostic features of the fluoride or carboxylate nucleophiles, and it must therefore be accepted that mechanistic certainty will be difficult to attain. It also must be remembered that many studies in the past were designed without regard to the inverted spin trapping mechanism and are difficult to judge owing to lack of critical experiments to test this particular aspect. 

The kinetic scheme of reaction (40), followed by reaction (42), was used to investigate the influence of added chloride ion on the epr spectral intensity of Cl-PBN. This variable decreased by a factor of about 50 in going from 

In agreement with this scheme, no chloro spin adduct was obtained when HFP was used as the solvent (Eberson et al., 1996a), as expected in view of the vast reactivity decrease of chloride ion in HFP (Table 9). 

The electrochemical behaviour of PBN +-cyanide ion is identical to that found in the two cases of inverted spin trapping described above, namely that attack at PBN + occurs via the softer carbon atom of CN . This contrasts with an observation of the cyano adduct to PBN formed by irradiation of Mo(CN) - 

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