title: Reactions of 13-vertex carboranes with strong bases: synthesis and structural characterization of carborane monoanions with exo-π bonding.
abstract: Several monoanions of 13-vertex carboranes were prepared in high yields from the reactions of C,C'-linked 13-vertex carboranes with tBuOK or NaH in dry THF at room temperature. These monoanions were characterized by various spectroscopic methods, elemental analysis, and single-crystal X-ray diffraction. The results showed substantial double-bond character between the cage-carbon atom and the exo vicinal carbon atom, thus leading to charge delocalization into the cage. As a result, the atom-atom distances within the cage were elongated, with one broken C-B bond. However, the cage geometry of the monoanions remained very similar to that of their corresponding neutral 13-vertex closo-carboranes. These monoanions represent the first examples of 13-vertex carboranes with exo-π bonding to hypercarbon atoms.
authors.affiliation: Department of Chemistry and State Key Laboratory of Synthetic Chemistry, The Chinese University of Hong Kong, Shatin, NT, Hong Kong, China.
authors.forename: Fangrui
authors.initials: F
authors.lastname: Zheng
authors.forename: Jian
authors.initials: J
authors.lastname: Zhang
authors.forename: Xiaodu
authors.initials: X
authors.lastname: Fu
authors.forename: Zuowei
authors.initials: Z
authors.lastname: Xie
keywords: boron; cage compounds; carboranes; deprotonation; pi interactions