Oxidation Products of Doubly Trimethylene-Bridged Tetrabenzyl p-Phenylenediamine Paracyclophane

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• 作者：Almaz S. Jalilov ; Lu Han ; Stephen F. Nelsen ; Ilia A. Guzei
• 刊名：Journal of Organic Chemistry
• 出版年：2013
• 出版时间：November 15, 2013
• 年：2013
• 卷：78
• 期：22
• 页码：11373-11381
• 全文大小：484K
• 年卷期：v.78,no.22(November 15, 2013)
• ISSN：1520-6904

文摘

We report synthesis and investigation of doubly trimethylene-bridged tetrabenzyl-p-phenylenediamine 1(Bz) in its singly and doubly charged redox states. The singly oxidized monoradical cation, which is a mixed-valence (MV) system with directly interacting charge-bearing units, shows broad and solvent-sensitive intervalence bands consistent with class II compounds according to the Robin鈥揇ay classification. The doubly oxidized diradical dication of 1(Bz) exists in the spin-paired singlet state with thermally accessible triplet state. It has similar conformations as the other dimeric p-phenylenediamines, such as derivatives 1(Me) and 1(Et), in both the solid-state and solution phases. The successful isolation of the single-crystalline 1(Bz)<sup>2+sup> diradical dications with two different in nature counteranions, relatively highly coordinating SbF<sub>6sub><sup>鈥?/sup> and weakly coordinating carborane [undecamethylcarborane HCB<sub>11sub>Me<sub>11sub><sup>鈥?/sup> (CB<sup>鈥?/sup>)], reveals the distinct effect of the nature of counterions on the structural features of diradical dication. Cyclic voltammetry measurements of 1(Bz) in dichloromethane reveal separation of the first and second oxidation potential by 0.12 V (2.8 kcal/mol), indicating relatively stable mixed-valence state in the dichloromethane, whereas in the acetonitrile both the first and second oxidation potentials overlap into one unresolved redox peak with minimal separation.