Electrofugal moieties

Owing to the hardness of Si(IV) and Sn(IV) nuclei, triorganosilyl and triorganostannyl groups can act as electrofugal moieties during heterolysis initiated by an electron-deficient /J atom (62,63). 

To summarize, by modifying in -C-O- either the leaving group abilities of the carbon moiety (the electrofuge) (e.g., by alkyl substitution at or by ionization of OH) or those of the nitrobenzene (by substitution at the ring) it is possible to go all the way from pure addition to what appears to be pure electron transfer. The heterolysis rates increase with increasing electron push ... 

A leaving group that departs with the bonding electron pair. The tendency of such a moiety to leave is referred to as nucleofugicity. See also Electrofuge Nucleophile... 

Fragmentation A reaction in which the carbon moiety is the positive leaving group (i.e. the electrofuge) in an elimination reaction. 

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