The electrochemistry and acid‐base chemistry of TCNQF and TCNQF₂ (TCNQ=7,7,8,8‐tetracyanoquinodimethane) are described, and the results are compared to those reported previously for TCNQ and TCNQF₄. In acetonitrile solution, both mono‐ and di‐fluorinated TCNQ derivatives show two well‐resolved, diffusion‐controlled chemically and electrochemically reversible one‐electron‐transfer processes under the conditions of cyclic voltammetry. The reversible potentials of the mono‐ and difluoro‐TCNQ were determined for both the monoanionic and dianionic processes, that is, TCNQF^0/1−/2− and TCNQF₂^0/1−/2−. A Hammett plot shows a linear relationship of the potential differences between the three fluorinated derivatives and TCNQ with the sum of the Hammett constants for fluoro substitution. A significant positive shift in the reversible potential is found by increasing the number of fluoro substituents. Although the first TCNQF_n^0/1− (n=1,2) reduction process is not affected by addition of trifluoroacetic acid (TFA), the dianions are more basic and rapidly protonate to form H₂TCNQF_n. This explains the significant change detected in the electrochemistry of the second TCNQF_n^1−/2− redox process. The addition of TFA to solutions of the monoanionic form also gives rise to the disproportionation of TCNQF_n¹⁻ to TCNQF_n and H₂TCNQF_n, as proven electrochemically and spectroscopically. Furthermore, a higher number of fluoro substituents results in the reduced form of the molecule being more stable, as evidenced by both UV/Vis spectra and voltammetric measurements. Finally, we performed DFT calculations for TCNQF₂ and TCNQF₂ to produce a spectroscopic library of characteristic IR and Raman bands for these species. These data are used for comparisons with earlier calculations for TCNQF₄, and we report the experimental and calculated infrared and Raman spectra for TCNQF and TCNQF₂. The vibrational frequencies of the trifluorinated species, TCNQF₃, were also calculated to complete the series.

中文翻译：

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研究TCNQF和TCNQF2的氧化还原和酸碱性质：电化学，振动光谱和取代基效应

描述了TCNQF和TCNQF ₂（TCNQ = 7,7,8,8-四氰基喹_二甲烷）的电化学和酸碱化学性质，并将结果与​​先前报道的TCNQ和TCNQF _{4进行了比较}。在乙腈溶液中，单氟和二氟TCNQ衍生物在循环伏安法条件下均显示出两个分辨良好的，扩散控制的化学和电化学可逆的单电子转移过程。确定了单阴离子和双阴离子过程的单氟和二氟TCNQ的可逆电位，即TCNQF ^{0 / 1- / 2-}和TCNQF ₂ ^{0 / 1- / 2-}。哈米特图显示了三种氟化衍生物与TCNQ之间的电势差与氟取代的哈米特常数之和的线性关系。通过增加氟取代基的数量，发现可逆电势有明显的正向变化。尽管第一个TCNQF _n ^{0 / 1-}（n = 1,2）还原过程不受添加三氟乙酸（TFA）的影响，但_二价阴离子更碱性且能快速质子化以形成H ₂ TCNQF _n。这解释了在第二TCNQF _n ^{1- / 2-}的电化学中检测到的显着变化氧化还原过程。如电化学和光谱法所证实的，将TFA添加到单阴离子形式的溶液中还引起TCNQF _n ^1-与TCNQF _n和H ₂ TCNQF _n的歧化。此外，如UV / Vis光谱和伏安法测量所证实的，更多数量的氟取代基导致分子的还原形式更稳定。最后，我们对TCNQF ₂和TCNQF ₂进行了DFT计算，以生成这些物种的特征IR和拉曼谱带的光谱库。这些数据用于与TCNQF _4的早期计算进行比较，我们报告了TCNQF和TCNQF ₂的实验和计算的红外光谱和拉曼光谱。还计算了三氟化物TCNQF ₃的振动频率，以完成级数。