Molecular Dials: Hindered Rotations in Mono- and Diferrocenyl Anthracenes and Triptycenes

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• 作者：Kirill Nikitin ; Helge Mller-Bunz ; Yannick Ortin ; Jimmy Muldoon ; Michael J. McGlinchey
• 刊名：Journal of the American Chemical Society
• 出版年：2010
• 出版时间：December 15, 2010
• 年：2010
• 卷：132
• 期：49
• 页码：17617-17622
• 全文大小：308K
• 年卷期：v.132,no.49(December 15, 2010)
• ISSN：1520-5126

文摘

The syntheses, X-ray crystal structures, and molecular dynamics of 9-ferrocenylanthracene, 3, 9,10-diferrocenylanthracene, 4, 9-ferrocenyltriptycene, 7, and 9,10-diferrocenyltriptycene, 8, are reported. At 193 K, 3 exhibits C_s symmetry via oscillation of the ferrocenyl only about the anthracene plane; at higher temperatures, complete rotation about the C(9)−ferrocenyl linkage becomes evident with a barrier of 10.6 kcal mol⁻¹. At 193 K, the ferrocenyls in 4 give rise to syn (C_2v) and anti (C_2h) rotamers that also interconvert at room temperature. In the corresponding triptycyl systems, 7 and 8, these rotational barriers increase to 17 kcal mol⁻¹; 9,10-diferrocenyltriptycene exists as slowly interconverting meso and racemic rotamers, in which the ferrocenyl moieties are, respectively, eclipsed (C_2v) or staggered (C₂). 2D-EXSY NMR data recorded with different mixing times indicate clearly that these interconversions proceed in a stepwise manner, for example, rac→meso→rac, thus behaving as a set of molecular dials.