title: Reduction of bowl-shaped hydrocarbons: dianions and tetraanions of annelated corannulenes.
abstract: [structure: see text] The reduction of several annelated corannulene derivatives was undertaken using lithium and potassium metals. It was found that annelation affects the annulenic character of corannulene by changing its charge distribution; the dianions of derivatives that are annelated with six-membered rings have less annulenic character and are less paratropic than corannulene dianion. This effect is even more pronounced in corannulenes that are peri-annelated with five-membered rings. The alkali metal used in the reduction process has a great influence on the outcome, especially on the degree of reduction. Most derivatives get reduced to tetraanions only with potassium, and not with lithium, the exception being systems that can stabilize the tetraanion with lithium by special means, such as aggregation or dimerization. One such system is cyclopenta[bc]corannulene (acecorannulylene), which gives a coordinative dimer that consists of 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.
authors.affiliation: Department of Organic Chemistry, Hebrew University of Jerusalem, Jerusalem 91904, Israel.
authors.forename: Ivan
authors.initials: I
authors.lastname: Aprahamian
authors.forename: Dorin V
authors.initials: DV
authors.lastname: Preda
authors.forename: Mihail
authors.initials: M
authors.lastname: Bancu
authors.forename: Anthony P
authors.initials: AP
authors.lastname: Belanger
authors.forename: Tuvia
authors.initials: T
authors.lastname: Sheradsky
authors.forename: Lawrence T
authors.initials: LT
authors.lastname: Scott
authors.forename: Mordecai
authors.initials: M
authors.lastname: Rabinovitz