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首页> 外文期刊>Chemistry: A European journal >Remarkable interplay of redox states and conformational changes in a sterically crowded, cross-conjugated tetrathiafulvalene vinylog
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Remarkable interplay of redox states and conformational changes in a sterically crowded, cross-conjugated tetrathiafulvalene vinylog

机译：在空间拥挤，交叉共轭的四硫富瓦烯烯乙烯基胶中，氧化还原状态和构象变化之间的显着相互作用

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Derivatives of 9-[2-(1,3-dithiol-2-ylidene)ethylidene]thioxanthene have been synthesized using Horner-Wadsworth-Emmons reactions of (1,3-dithiol-2-yl)phosphonate reagents with thioxanthen-9-vlidene-acetaidehyde. (5). Further reactions lead to the sterically crowded cross-conjugated "vinylogous ietrathiafulvalene" derivative 9[2,3-bis -(4.5-dimethyl-1,3-dithiol-2-ylidene)-propylidene]thioxanthene (10). X-ray crystallography, solution electrochemistry optical spectroscopy, spectroelectrochemistry and simultaneous electrochemistry and electron paramagnetic resonance spectroscopy, combined with theoretical calculations performed at the B3LYP/6-31G(d) level, eluciclare the interplay of the electronic and structural properties in these molecules. For compound 10, multistage redox behavior is observed: the overall electrochemical process can be represented by 10 -> 10(.+->)10(2+)-> 10(4+) with good reversibility for the 10 -> 10(.+)-> 10(2+) transformations. At the tetracation stage there is the maximum gain in aromaticity at the dithiolium and thioxanthenium rings. Theory predicts that for 10, 10(.+), and 10(2+) the trans isomers are more stable than the cis isomers (by ca. 2-18 kJmol(-1)), whereas for 104, the cis isomer becomes more stable than the trans isomer (by ca. 25 kJ mol(-1)) [trans and cis refer to the arrangement of the two dithiole moieties with respect to the central =C(R)C(H) fragment]. These data explain the detection in cyclic voltammograms of both trans and cis isomers of 10 and 10(.+) during the reduction of 10(4+) at fast scan rates (> 100 mVs(-1)) when the cis-trans isomerization is not completed within the timescale of the experiment. The X-ray structure of the charge-transfer complex (CTC) of 10 with 2,4,5,7-tetranitrofluorene-9-dicyanomethylenefluorene (DTeF) [stoichiometry: 10(.+).(DTeF)(2)(.-).2PhCl] reveals a twisted conformation of 10(.+) (driven by the bulky thioxanthene moiety) and provides a very rare example of segregated stacking of a fluorene acceptor in a CTC.
机译：使用（1,3-二硫醇-2-基）膦酸酯试剂与噻吨菌素9-的Horner-Wadsworth-Emmons反应合成了9- [2-（1,3-二硫醇-2-亚乙基）亚乙基]噻吨蒽的衍生物。亚乙烯基乙酸酐。 （5）。进一步的反应导致空间上拥挤的交叉共轭的“乙烯基异黄硫富瓦烯”衍生物9 [2，3-双-（4.5-二甲基-1，3-二硫醇-2-亚烷基）-亚丙基]噻吨并（10）。 X射线晶体学，溶液电化学光谱法，光谱电化学法，同时电化学和电子顺磁共振光谱法以及在B3LYP / 6-31G（d）级进行的理论计算相结合，阐明了这些分子中电子和结构性质之间的相互作用。对于化合物10，观察到多级氧化还原行为：整个电化学过程可以用10-> 10（。+->）10（2 +）-> 10（4+）表示，对于10-> 10（ 。+）-> 10（2+）转换。在四阳离子阶段，在二硫鎓和噻吨鎓环上获得最大的芳香性。理论预测，对于10、10（。+）和10（2+），反式异构体比顺式异构体更稳定（大约2-18 kJmol（-1）），而对于104，顺式异构体变为比反式异构体更稳定（约25 kJ mol（-1））[反式和顺式是指相对于中心= C（R）C（H）片段，两个二硫键部分的排列]。这些数据解释了在快速扫描速率（> 100 mVs（-1））还原10（4+）时顺式-反式异构化过程中10和10（。+）的反式和顺式异构体的循环伏安图检测未在实验的时间范围内完成。 10与2,4,5,7-四硝基芴-9-二氰基亚甲基芴（DTeF）的电荷转移络合物（CTC）的X射线结构[化学计量：10（。+）。（DTeF）（2）（。 -）。2PhCl]揭示了10（。+）的扭曲构象（由庞大的噻吨基部分驱动），并提供了在CTC中芴受体的分离堆叠的非常罕见的例子。

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