Phenazin−5(10H)−yls, 5. − Intermolecular − π−π Interactions (Pimerization) of tert−Butyl−Substituted Phenazin−5(10H)−yl Radicals in The Solid State: Syntheses, Crystal Structures and Magnetic Susceptibility Measurements
Phenazin−5(10H)−yls, 5. − Intermolecular − π−π Interactions (Pimerization) of tert−Butyl−Substituted Phenazin−5(10H)−yl Radicals in The Solid State: Syntheses, Crystal Structures and Magnetic Susceptibility Measurements
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吩嗪−5(10H)−yls, 5. − 固态叔丁基取代吩嗪−5(10H)−yl 自由基的分子间 − π−π 相互作用（二聚化）：合成、晶体结构和磁化率测量
DOI：
10.1002/jlac.199719970307
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发表时间：
1997
影响因子：
2.8
通讯作者：
F. A. Neugebauer
中科院分区：
文献类型：
--
作者：
Marco R. Gleiter;B. Kanellakopulos;C. Krieger;F. A. Neugebauer
在AlCl3存在下，5-乙酰基-5，10-二氢吩嗪(2a)与叔丁基氯反应，在吩嗪骨架中引入叔丁基。以2，8-或3，7-二叔丁基取代物2c和2b为原料，合成了一系列吩嗪-5(10H)-基自由基(1c-I)，并用ESR和En-DOR光谱进行了表征。除1c外，所有吩嗪-5(10H)-YL都是以晶体形式得到的，并且对于1d-f，在λ≈870 nm处的长波吸收带指示了固态中分子间的π-π相互作用。1d、1e和1h的晶体结构均可确定。1D的晶胞由8个吩嗪-5(10H)-YL组成。令人惊讶的是，其中四个是成对排列的，而另外四个是独立地位于晶格中的。在1E中，晶胞内的四个吩嗪-5(10H)-YL排列在两个独立的自由基对A和B中，这两个自由基对具有密切的平面间距和较短的分子间接触，具有显著的自旋布居。相应地，磁化率数据表明在低温下有很强的自旋配对。由于吩嗪-5(10H)-基骨架的广泛空间屏蔽，1H的晶体结构没有证据表明相邻自由基之间有任何π-π相互作用。不出所料，1h的磁化率相当于普通单轨的磁化率。
Introduction of tert-butyl groups into the phenazine frame-work was accomplished by treatment of 5-acetyl-5,10-dihydrophenazine (2a) with tert-butyl chloride in the presence of AlCl3. Starting from the 2,8- or 3,7-di-tert-butyl-substituted derivatives 2c and 2b, a series of phenazin-5(10H)-yl radicals (1c–i) was synthesized and characterized by ESR and EN-DOR spectroscopy. With the exception of 1c, all phenazin-5(10H)-yls were obtained in crystalline form, and for 1d–f the long-wavelength absorption band at λ ≈ 870 nm indicates intermolecular π-π interactions in the solid state. For 1d, 1e and 1h the crystal structure could be determined. The unit cell of 1d consists of eight phenazin-5(10H)-yls. Surprisingly, four of them are arranged in radical pairs, whereas the other four lie independently in the lattice. In agreement with this structure, the magnetic susceptibility results correspond to a content of 50% monoradical and an almost complete spinpairing in the radical pairs up to T = 220 K. In 1e, the four phenazin-5(10H)-yls in the unit cell are arranged in two independent radical pairs, A and B, which are characterized by close interplanar distances and short intermolecular contacts between atoms with significant spin populations. Accordingly, the susceptibility data indicate strong spin-pairing at low temperature. Due to extensive steric shielding of the phenazin-5(10H)-yl framework, the crystal structure of 1h gives no evidence of any π-π interactions between adjacent radicals. As expected, the magnetic susceptibility of 1h corresponds to that of an ordinary monoradical.