Interaction of 1,2,5-Chalcogenadiazole Derivatives with Thiophenolate: Hypercoordination with Formation of Interchalcogen Bond versus Reduction to Radical Anion

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• 作者：Elizaveta A. Suturina ; Nikolay A. Semenov ; Anton V. Lonchakov ; Irina Yu. Bagryanskaya ; Yuri V. Gatilov ; Irina G. Irtegova ; Nadezhda V. Vasilieva ; Enno Lork ; Ru虉diger Mews ; Nina P. Gritsan ; Andrey V. Zibarev
• 刊名：Journal of Physical Chemistry A
• 出版年：2011
• 出版时间：May 12, 2011
• 年：2011
• 卷：115
• 期：18
• 页码：4851-4860
• 全文大小：1047K
• 年卷期：v.115,no.18(May 12, 2011)
• ISSN：1520-5215

文摘

According to the DFT calculations, [1,2,5]thiadiazolo[3,4-c][1,2,5]thiadiazole (4), [1,2,5]selenadiazolo[3,4-c][1,2,5]thiadiazole (5), 3,4-dicyano-1,2,5-thiadiazole (6), and 3,4-dicyano-1,2,5-selenadiazole (7) have nearly the same positive electron affinity (EA). Under the CV conditions they readily produce long-lived 蟺-delocalized radical anions (蟺-RAs) characterized by EPR. Whereas 4 and 5 were chemically reduced into the 蟺-RAs with thiophenolate (PhSp>鈥?/sup>), 6 did not react and 7 formed a product of hypercoordination at the Se center (9) isolated in the form of the thermally stable salt [K(18-crown-6)][9] (10). The latter type of reactivity has never been observed previously for any 1,2,5-chalcogenadiazole derivatives. The X-ray structure of salt 10 revealed that the Se鈥揝 distance in the anion 9 (2.722 脜) is ca. 0.5 脜 longer than the sum of the covalent radii of these atoms but ca. 1 脜 shorter than the sum of their van der Waals radii. According to the QTAIM and NBO analysis, the Se鈥揝 bond in 9 can be considered a donor鈥揳cceptor bond whose formation leads to transfer of ca. 40% of negative charge from PhSp>鈥?/sup> onto the heterocycle. For various PhSp>鈥?/sup>/1,2,5-chalcogenadiazole reaction systems, thermodynamics and kinetics were theoretically studied to rationalize the interchalcogen hypercoordination vs reduction to 蟺-RA dichotomy. It is predicted that interaction between PhSp>鈥?/sup> and 3,4-dicyano-1,2,5-telluradiazole (12), whose EA slightly exceeds that of 6 and 7, will lead to hypercoordinate anion (17) with the interchalcogen Te鈥揝 bond being stronger than the Se鈥揝 bond observed in anion 9.