From Corannulene to Indacenopicene: Effect of Carbon Framework Topology on Aromaticity and Reduction Limits
摘要:
The electronic structure, reduction limits, and coordination abilities of a bowl-shaped polycyclic aromatic hydrocarbon, indacenopicene (C26H12, 1), have been investigated for the first time using a combination of theoretical and experimental tools. A direct comparison with the prototypical corannulene bowl (C20H10, 2) revealed the effects of carbon framework topology and symmetry change on the electronic properties and aromaticity of indacenopicene. The accessibility of two reduction steps for 1 was predicted theoretically and then confirmed experimentally. Two reversible one-electron reduction processes with the formal reduction potentials at -1.92 and -2.29 V vs Fc(+/0) were detected by cyclic voltammetry measurements, demonstrating the stability of the corresponding, mono- and dianionic states of 1. The products of the doubly reduced indacenopicene have been isolated as rubidium and cesium,salts and fully characterized. Their X-ray diffraction study revealed the formation of tetranuclear organometallic building blocks with the [M-2(18-crown-6)](2+) (M = Rb (3) and Cs (4)) cations occupying the concave cavities of two C26H122- anions. The coordination of two outside exo-bound rubidium ions is terminated by crown ether molecules in 3 to form the discrete [Rb-4(+)(18-crown-6)(3)(C26H122-](2) tetramer. In contrast, the larger cesium ions allow the 1D polymeric chain propagation in 4 to afford [Cs-2(+)(18-crown-6)(2)(THF)(C26H122-)](infinity).
Facile Bucky-Bowl Synthesis by Regiospecific Cove-Region Closure by HF Elimination
作者:K. Yu. Amsharov、M. A. Kabdulov、Martin Jansen
DOI:10.1002/anie.201200516
日期:2012.5.7
intramolecular aryl–aryl coupling is the key step in rational fullerene synthesis and in synthesis of extended buckybowl structures. Such a process can be embodied very efficiently through quantitative HFelimination on active Al2O3. The process is characterized by an unprecedentedly high chemoselectivity and regiospecificity.
积木:有效的分子内芳基-芳基偶联是合理的富勒烯合成和延伸的Buckybowl结构合成中的关键步骤。通过对活性Al 2 O 3进行定量的HF消除,可以非常有效地实现这一过程。该过程的特点是前所未有的高化学选择性和区域特异性。
Acenaphthenoannulation Induced by the Dual Lewis Acidity of Alumina
We have discovered a dual (i. e., soft and hard) Lewisacidity of alumina that enables rapid one-pot π-extension through the activation of terminal alkynes followed by C-F activation. The tandem reaction introduces an acenaphthene fragment - an essential moiety of geodesic polyarenes. This reaction provides quick access to elusive non-alternant polyarenes such as π-extended buckybowls and helicenes