Synthesis,Structure, and Complexation of an S-Shaped Double Azahelicene with Inner-Edge Nitrogen Atoms |
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Authors: | Takahiro Kawashima Yuki Matsumoto Dr. Takuma Sato Dr. Yoichi M. A. Yamada Choji Kono Dr. Akihiro Tsurusaki Prof. Dr. Ken Kamikawa |
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Affiliation: | 1. Department of Chemistry, Graduate School of Science, Osaka Prefecture University, Sakai, Osaka, 599-8531 Japan;2. RIKEN Center for Sustainable Resource Science, Wako, Saitama, 351-0198 Japan |
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Abstract: | An S-shaped double azahelicene ( 1 ) was synthesized in excellent yield by a palladium-catalyzed double dehydrogenative C−H coupling reaction. The stereochemistry of 1 was confirmed to be dl by single-crystal X-ray diffraction analysis. Selective formation of dl- 1 was attributed to the isomerization of the kinetically controlled product (meso- 1 ) into the more thermodynamically stable dl- 1 under the applied reaction conditions. dl- 1 can coordinate to palladium(II) in a bidentate trans-chelating fashion, which was confirmed by X-ray absorption fine structure (XAFS) as well as by X-ray photoelectron spectroscopy (XPS), diffuse reflectance (DR) UV/Vis, and far-infrared (FIR) absorption spectroscopy. Theoretical calculations of palladium complex 16 revealed a weak attractive interaction between palladium and carbon atoms on the central dimethoxynaphthalene core, which could facilitate a disproportionation between a trans-chelating (dl- 1 ) ⋅ PdCl2 complex and PdCl2 to form 16 . |
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Keywords: | dehydrogenative C−H coupling N ligands palladium S-shaped diazahelicene |
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