A new series of π-extended tetrathiafulvalene derivatives incorporating fused furanodithiino and thienodithiino units: a joint experimental and theoretical study
作者:Rory Berridge、Igor M. Serebryakov、Peter J. Skabara、Enrique Ortí、Rafael Viruela、Rosendo Pou-Amérigo、Simon J. Coles、Michael B. Hursthouse
DOI:10.1039/b404545a
日期:——
A new family of tetrathiafulvalenes has been prepared. The materials exhibit complex redox behaviour related to the electronic influence of the 1,4-dithiin moieties embedded within the framework of the molecules. The X-ray crystal structure of compound 4 reveals an unusual non-planar conformation of the heterocyclic compound, with the TTF fragment adopting a boat conformation. Theoretical calculations, performed at the DFT level (B3P86/6-31G*), confirm the boatlike structure (C2v symmetry) as the most stable conformation for this family of tetrathiafulvalenes. Upon oxidation, electrons are extracted from the whole molecule and the radical cations and dications remain highly distorted from planarity. For the dications, the 1,4-dithiin units present foldings of â¼40° suggesting the possibility of reaching higher oxidation states in agreement with experimental results. For the tetracations, both the TTF nucleus and the 1,4-dithiin units are singly-charged and become planar. The tetracations therefore present fully-planar, Ï-delocalised structures and are stabilised by the gain of aromaticity of the TTF and 1,4-dithiin electron-donor units.
我们制备出了一个新的四硫富戊烯家族。这些材料表现出复杂的氧化还原行为,这与分子框架中嵌入的 1,4-二硫杂蒽分子的电子影响有关。化合物 4 的 X 射线晶体结构显示了杂环化合物不寻常的非平面构象,TTF 片段采用了船形构象。在 DFT 水平(B3P86/6-31G*)上进行的理论计算证实,舟状结构(C2v 对称性)是这类四硫富戊烯最稳定的构象。氧化时,电子从整个分子中被提取出来,而自由基阳离子和阴离子则保持高度平面变形。对于二阳离子,1,4-二硫单位呈现¼40°的折叠,表明有可能达到更高的氧化态,这与实验结果一致。对于四阳离子来说,TTF 核和 1,4-二硫单位都是单电荷的,并成为平面。因此,四阳离子呈现出完全平面的Ï-异位结构,并通过 TTF 和 1,4-二硫杂芑电子负载单元的芳香性增益而得到稳定。