激进的
二聚体
化学
光化学
单体
取代基
胺气处理
甲苯
结晶学
立体化学
有机化学
聚合物
作者
Kohei Okino,Shota Hira,Yuki Inoue,Daisuke Sakamaki,Shu Seki
标识
DOI:10.1002/anie.201710354
摘要
Herein, we demonstrate that the dimerization behavior of amine-substituted dicyanomethyl radicals can be switched from σ- to π-dimerization simply by varying the electron-donating substituents. For dicyanomethyl radicals with a 4,4'-ditolylamine (DT. ) or a phenothiazine (PT. ) substituent, the monomeric radical form and the corresponding dimer connected by a reversible C-C bond (σ-dimer) are in equilibrium in solution. On the other hand, the radical with the julolidine skeleton (JD. ) does not undergo σ-dimerization and was isolated as a stable radical in spite of the absence of bulky protecting groups. X-ray single-crystal analysis revealed that JD. forms the π-dimer in the crystalline state, and variable-temperature spectroscopy showed that JD. is in equilibrium with the π-dimer in toluene solution. DFT calculations point to the importance of electrostatic interactions as a driving force for the π-dimerization of JD. because of its polarized structure.
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