A chemical species with higher than usual electrophilic reactivity, often involving two positively charged centers. Superelectrophiles are intermediates in some enzymatic reactions; e.g. those of S-adenosyl methionine, in which the sulfonium group is juxtaposed with an acidic group on the adenosine moiety to promote sulfur-carbon bond cleavage and the consequent transfer of the methyl or aminopropyl group.