title: Fullerene-carbene Lewis acid-base adducts.
abstract: The reaction between a bulky N-heterocylic carbene (NHC) and C(60) leads to the formation of a thermally stable zwitterionic Lewis acid-base adduct that is connected via a C-C single bond. Low-energy absorption bands with weak oscillator strengths similar to those of n-doped fullerenes were observed for the product, consistent with a net transfer of electron density to the C(60) core. Corroborating information was obtained using UV photoelectron spectroscopy, which revealed that the adduct has an ionization potential ∼1.5 eV lower than that of C(60). Density functional theory calculations showed that the C-C bond is polarized, with a total charge of +0.84e located on the NHC framework and -0.84e delocalized on the C(60) cage. The combination of reactivity, characterization, and theoretical studies demonstrates that fullerenes can behave as Lewis acids that react with C-based Lewis bases and that the overall process describes n-doping via C-C bond formation.
authors.affiliation: Center for Polymers and Organic Solids, Department of Chemistry & Biochemistry, University of California, Santa Barbara, California 93106, United States.
authors.forename: Huaping
authors.initials: H
authors.lastname: Li
authors.forename: Chad
authors.initials: C
authors.lastname: Risko
authors.forename: Jung Hwa
authors.initials: JH
authors.lastname: Seo
authors.forename: Casey
authors.initials: C
authors.lastname: Campbell
authors.forename: Guang
authors.initials: G
authors.lastname: Wu
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Brédas
authors.forename: Guillermo C
authors.initials: GC
authors.lastname: Bazan