Discovery of the K4 Structure Formed by a Triangular 蟺 Radical Anion

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• 作者：Asato Mizuno ; Yoshiaki Shuku ; Rie Suizu ; Michio M. Matsushita ; Masahisa Tsuchiizu ; Daniel Reta Ma帽eru ; Francesc Illas ; Vincent Robert ; Kunio Awaga
• 刊名：Journal of the American Chemical Society
• 出版年：2015
• 出版时间：June 24, 2015
• 年：2015
• 卷：137
• 期：24
• 页码：7612-7615
• 全文大小：305K
• ISSN：1520-5126

文摘

The K₄ structure was theoretically predicted for trivalent chemical species, such as sp² carbon. However, since attempts to synthesize the K₄ carbon have not succeeded, this allotrope has been regarded as a crystal form that might not exist in nature. In the present work, we carried out electrochemical crystallization of the radical anion salts of a triangular molecule, naphthalene diimide (NDI)-螖, using various electrolytes. X-ray crystal analysis of the obtained crystals revealed the K₄ structure, which was formed by the unique intermolecular 蟺 overlap directed toward three directions from the triangular-shape NDI-螖 radical anions. Electron paramagnetic resonance and static magnetic measurements confirmed the radical anion state of NDI-螖 and indicated an antiferromagnetic intermolecular interaction with the Weiss constant of 胃 = 鈭?0 K. The band structure calculation suggested characteristic features of the present material, such as a metallic ground state, Dirac cones, and flat bands.