Halogenated Symmetrical Tetraazapentacenes: Synthesis, Structures, and Properties

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• 作者：Jens U. Engelhart ; Fabian Paulus ; Manuel Schaffroth ; Vladislav Vasilenko ; Olena Tverskoy ; Frank Rominger ; Uwe H. F. Bunz
• 刊名：Journal of Organic Chemistry
• 出版年：2016
• 出版时间：February 5, 2016
• 年：2016
• 卷：81
• 期：3
• 页码：1198-1205
• 全文大小：535K
• ISSN：1520-6904

文摘

We herein describe the synthesis and property evaluation of several brominated and chlorinated tetraazapentacenes. The targets were obtained by thermal condensation of 2,5-dihydroxyquinone with 4,5-dichloro-, 2,6-dichloro-, and 4,5-dibromo-1,2-phenylenediamine, followed by oxidation with hot acidic dichromate. Double alkynylation, reductive deoxygenation, and subsequent oxidation using MnO₂ furnishes the target compounds. Absorption spectra, electrochemistry, and single crystal structures of the targets are reported. The 1,4,8,11-tetrachlorotetraazapentacene (1,4,8,11-tetrachloroquinoxalino[2,3-b]phenazine) carrying its chlorine atoms in the peri-positions packs in a herringbone type arrangement, while the isomer (2,3,9,10-tetrachloroquinoxalino[2,3-b]phenazine, with the chlorine atoms in the east and west positions) packs in one-dimensional stacks. In all cases, the reduction potentials and the calculated LUMO-positions are decreased by the introduction of the halogen atoms.