Compressing Double [7]Helicene by Successive Charging with Electrons
Compressing Double [7]Helicene by Successive Charging with Electrons
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通过电子连续充电压缩双[7]Helicene
DOI：
10.1002/anie.202005852
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发表时间：
2020
期刊：
影响因子：
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通讯作者：
Petrukhina Marina A.
中科院分区：
文献类型：
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作者：
Zhou Zheng;Fu Lin;Hu Yunbin;Wang Xiao-Ye;Wei Zheng;Narita Akimutsu;Müllen Klaus;Petrukhina Marina A.
用两种碱金属K和Rb对苯并稠合双[7]螺烯（1）进行化学还原，可以得到3种不同的1的还原态。双还原的螺烯12 −通过单晶X射线衍射表征为具有两个钾反离子的溶剂分离离子三重态。三重和四重还原的螺烯13−和14 −以等摩尔比结晶在一起，并且都与两个Rb+离子形成接触离子络合物，剩下三个剩余的Rb+离子被冠醚和THF分子包裹。作为1逐步还原的结构结果，螺旋烯的中心轴在加入电子后变得更加压缩（14 −vs. 2.09毫英寸1）。 这伴随着额外的核心扭曲，因为外围二面角从16.5° in 1增加到20.7° in 14 −。理论计算提供了每次电子添加时扭曲螺烯框架上负电荷积累和分布的模式，结果与X射线晶体学和NMR光谱数据一致。
Chemical reduction of a benzo‐fused double [7]helicene (1) with two alkali metals, K and Rb, provided access to three different reduced states of1. The doubly‐reduced helicene12−has been characterized by single‐crystal X‐ray diffraction as a solvent‐separated ion triplet with two potassium counterions. The triply‐ and tetra‐reduced helicenes,13−and14−, have been crystallized together in an equimolar ratio and both form the contact‐ion complexes with two Rb+ions each, leaving three remaining Rb+ions wrapped by crown ether and THF molecules. As structural consequence of the stepwise reduction of1, the central axis of helicene becomes more compressed upon electron addition (1.42 Å in14−vs. 2.09 Å in1). This is accompanied by an extra core twist, as the peripheral dihedral angle increases from 16.5° in1to 20.7° in14−. Theoretical calculations provided the pattern of negative charge build‐up and distribution over the contorted helicene framework upon each electron addition, and the results are consistent with the X‐ray crystallographic and NMR spectroscopic data.