Biradicaloids charge transfer

W. Rettig, F. Marschner, Molecular conformation and biradicaloid charge transfer states in substituted N-pheny 1-pyrroles, NewJ. Chem. 74,819(1990). 

The intermediacy of a species analogous to (i) (Scheme 1.7) that some described as a resonance hybrid of a radical pair and an ion pair and others as an ultrafast equilibrium between radical and ion pair has been proposed in the photoionization reaction of benzyl derivatives [172, 174-176]. Also, interestingly, to explain the driving force behind the rotational motion that leads to an extremely rapid deactivation of S of TAM cations, Vogel and Rettig [177] proposed that SI promptly forms a biradicaloid charge-transfer state. 

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