Department für Chemie und Pharmazie & Interdisciplinary Center for Molecular Materials (ICMM), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Henkestrasse 42, 91054 Erlangen, Germany.
Chem Soc Rev. 2014 May 7;43(9):3184-203. doi: 10.1039/c4cs00022f. Epub 2014 Mar 27.
Molecules composed of a contiguous sequence of double bonds, the [n]cumulenes, share structural similarities to both of their conjugated relatives, the polyenes and polyynes. The synthesis and properties of [n]cumulenes are, however, quite different from those of either polyenes or polyynes. At an infinite length, [n]cumulenes would provide one structural form of the hypothetical sp-hybridized carbon allotrope carbyne, while shorter derivatives offer model compounds to help to predict the properties of carbyne. Finally, derivatization of the π-electron framework of [n]cumulenes provides a number of different synthetic transformations, with cycloaddition reactions being the most common. In this review, both historical and recent synthetic achievements toward long [n]cumulenes (n ≥ 5) are discussed. This is followed by a description of our current understanding of the physical and electronic structure of [n]cumulenes based on UV/vis spectroscopy and X-ray crystallography. Finally, the reactivity of long [n]cumulenes is described.
由连续双键组成的分子，即[n]累积烯，与它们的共轭近亲多烯和多炔在结构上有相似之处。然而，[n]累积烯的合成和性质与多烯或多炔有很大的不同。在无限长的情况下，[n]累积烯将提供假设的 sp 杂化碳同素异形体炔烃的一种结构形式，而较短的衍生物则提供模型化合物来帮助预测炔烃的性质。最后，对[n]累积烯的π-电子结构进行衍生化，提供了多种不同的合成转化，其中环加成反应最为常见。在这篇综述中，讨论了长[n]累积烯（n ≥ 5）的历史和最近的合成成就。接下来描述了我们基于紫外/可见光谱和 X 射线晶体学对[n]累积烯的物理和电子结构的现有理解。最后，描述了长[n]累积烯的反应性。
