Tuning Binding of Rubidium Ions to Planar and Curved Negatively Charged 蟺 Surfaces
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- 作者：Sarah N. Spisak ; Natalie J. Sumner ; Alexander V. Zabula ; Alexander S. Filatov ; Andrey Yu. Rogachev ; Marina A. Petrukhina
- 刊名：Organometallics
- 出版年：2013
- 出版时间：July 22, 2013
- 年：2013
- 卷：32
- 期：14
- 页码：3773-3779
- 全文大小：340K
- 年卷期：v.32,no.14(July 22, 2013)
- ISSN：1520-6041
文摘
Two new rubidium salts of the bowl-shaped corannulene monoanion radical C20H10鈥⑩€?/sup> (1鈥⑩€?/sup>), [Rb(15-crown-5)2+][C20H10鈥?/sup>] (2) and [Rb(dicyclohexano-18-crown-6)+][C20H10鈥?/sup>] (3), have been synthesized and structurally characterized in this work. An excess of 15-crown-5 ether provided full encapsulation of the rubidium ion in [Rb(15-crown-5)2]+, which precluded metal-directed 蟺 interactions with the anionic surface of C20H10鈥⑩€?/sup> in the solid-state structure of 2. The use of more sterically demanding dicyclohexano-18-crown-6 ether prevented the formation of polymeric chains previously seen with 18-crown-6 ether and favored the isolation of the discrete contact ion pair 3. Complex 3 is built on a convex 畏6 coordination of Rb+ to C20H10鈥⑩€?/sup>, reaffirming the exo-binding preference of rubidium ions toward the singly charged corannulene bowl. A rubidium salt of the planar coronene monoanion radical C24H12鈥⑩€?/sup> (4鈥⑩€?/sup>), [Rb(18-crown-6)+][C24H12鈥?/sup>] (5), has also been prepared and structurally characterized to reveal a new binding mode of C24H12鈥⑩€?/sup>. The analysis of the X-ray structure of 5, augmented by DFT calculations, confirmed the existence of strong C鈥揌路路路蟺 interactions between the crown ether and charged surface of C24H12鈥⑩€?/sup>. These interactions result in a good alignment of matching in size crown ether and coronene moieties, thereby being responsible for the formation of a hub-bound coronene product. DFT calculations were also used to follow the spin density distribution in the [Rb(18-crown-6)][C24H12] system as well as in original fragments.