| Abstract
| - The reduction of several annelated corannulene derivatives was undertaken using lithium and potassiummetals. It was found that annelation affects the annulenic character of corannulene by changing its chargedistribution; the dianions of derivatives that are annelated with six-membered rings have less annuleniccharacter and are less paratropic than corannulene dianion. This effect is even more pronounced incorannulenes that are peri-annelated with five-membered rings. The alkali metal used in the reductionprocess has a great influence on the outcome, especially on the degree of reduction. Most derivatives getreduced to tetraanions only with potassium, and not with lithium, the exception being systems that canstabilize the tetraanion with lithium by special means, such as aggregation or dimerization. One suchsystem is cyclopenta[bc]corannulene (acecorannulylene), which gives a coordinative dimer that consistsof two cyclopentacorannulene tetraanions, bound together in a convex−convex fashion by lithium cations.The points of contact in this dimer are two rehybridized carbons from each cyclopentacorannulene unit,which are bridged together by two lithium cations.
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