theoretical calculations predicted a very weak C–C bond with a bondlength around 1.8 Å. This bond is expanded by the forced adoption of an eclipsed conformation and by angle strain through a “scissor effect.” The highly strained hydrocarbon was isolated as a thermally stable compound with no signs of diradical contribution because the weak C–C bond (core) is protected by the shape-persistent fused-ring
基于分子内“核-壳策略”,我们设计了带有两个螺环(二苯并环庚三烯)单元的二氢次萘,理论计算结果表明,该键具有很弱的C–C键,键长约为1.8Å。通过强制采用暗淡的构象以及通过“剪刀效应”引起的角度应变,可以扩大这种结合。高应变烃是一种热稳定的化合物,没有任何自由基的迹象,因为弱的C–C键(核)受到形状持久的稠环结构(壳)的保护。对应于C–C拉伸振动(587 cm -1)的拉曼位移与乙烷(993 cm -1)的拉曼位移非常不同)。通过X射线测定的键长(1.806(2)Å)大于最短的非键分子内C … C接触(1.80(2)Å)。通过假设键长与共价键的键解离能之间呈线性相关,假定的C–C键极限(1.803Å)是无效的。
Gold‐Catalyzed Annulation of 1,8‐Dialkynylnaphthalenes: Synthesis and Photoelectric Properties of Indenophenalene‐Based Derivatives
作者:Sara Tavakkoli Fard、Kohei Sekine、Kaveh Farshadfar、Frank Rominger、Matthias Rudolph、Alireza Ariafard、A. Stephen K. Hashmi
DOI:10.1002/chem.202004846
日期:2021.2.15
Indenophenalene derivatives were obtained in moderate to high yields. In addition, the bidirectional gold‐catalyzed annulation of tetraynes provided even larger conjugated π‐systems. The optoelectronic properties of the products were also investigated.
This work describes the syntheses, crystal structures, photophysical properties, and electro‐chemical analyses of benzo[k]fluoranthene‐based linear acenes, together with ab initio density functional theory computations on them. The molecules were prepared in generally moderate to good yields through Pd‐catalyzed cycloadditions between 1,8‐diethynylnaphthalene derivatives and aryl iodides. This protocol
这项工作描述了基于苯并[ k ]荧蒽的线性并苯的合成,晶体结构,光物理性质和电化学分析,以及从头开始的密度泛函理论计算。通过在1,8-二乙炔基萘衍生物和芳基碘化物之间进行Pd催化的环加成反应,通常可以以中等到良好的产率制备这些分子。该协议比常规方法更简单,更有效。检查了该反应的范围和局限性。化合物4 hb,15 ac,17 ab,19 ac和24 je的结构通过X射线分析确定; 它们是弯曲的还是扭曲的,而不是平面的。还研究了这些环加合物的光物理和电化学性质,并将其与基于密度泛函理论的计算预测进行了比较。