Careful control of the reaction stoichiometry and conditions enables the synthesis of both LiTCNQF(4) and Li(2)TCNQF(4) to be achieved. Reaction of LiI with TCNQF(4), in a 4:1 molar ratio, in boiling acetonitrile yields Li2TCNQF4. However, deviation from this ratio or the reaction temperature gives either LiTCNQF(4) or a mixture of Li(2)TCNQF(4) and LiTCNQF(4). This is the first report of the large-scale chemical synthesis of Li(2)TCNQF(4). Attempts to prepare a single crystal of Li(2)TCNQF(4) have been unsuccessful, although air stable (Pr4N)(2)TCNQF(4) was obtained by mixing Pr4NBr with Li(2)TCNQF(4) in aqueous solution. Pr(4)NTCNQF(4) was also obtained by reaction of LiTCNQF(4) with Pr4NBr in water. Li(2)TCNQF(4), (Pr4N)(2)TCNQF(4), and Pr(4)NTCNQF(4) have been characterized by UV-vis, FT-IR, Raman, and NMR spectroscopy, high resolution electrospray ionization mass spectrometry, and electrochemistry. The structures of single crystals of (Pr4N)(2)TCNQF(4) and Pr(4)NTCNQF(4) have been determined by X-ray crystallography. These TCNQF(4)(2-) salts will provide useful precursors for the synthesis of derivatives of the dianions.
Lu, J., Le, T. H., Traore, D. A. K., Wilce, M. C. J., Bond, A. M., & Martin, L. L. (2012). Synthetic precursors for TCNQF(4)(2-) compounds: synthesis, characterization, and electrochemical studies of (Pr4N)(2)TCNQF(4) and Li(2)TCNQF(4). The Journal of Organic Chemistry, 77(23), 10568 - 10574. https://doi.org/10.1021/jo301403v