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Isotropic Three‐Dimensional Molecular Conductor Based on the Coronene Radical Cation
Author(s) -
Yoshida Yukihiro,
Maesato Mitsuhiko,
Kumagai Yoshihide,
Mizuno Motohiro,
Isomura Kazuhide,
Kishida Hideo,
Izumi Masanari,
Kubozono Yoshihiro,
Otsuka Akihiro,
Yamochi Hideki,
Saito Gunzi,
Kirakci Kaplan,
Cordier Stéphane,
Perrin Christiane
Publication year - 2014
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201400119
Subject(s) - chemistry , coronene , disproportionation , molecule , crystallography , molecular physics , biochemistry , organic chemistry , catalysis
In this study, we obtained the first cation radical solid of a highly symmetric ( D 6 h ) polyaromatic hydrocarbon, coronene, by electrooxidation. The (coronene) 3 Mo 6 Cl 14 salt, which is formed with an O h ‐symmetric molybdenum cluster unit Mo 6 Cl 14 2– , has an isotropic cubic structure with Pm $\bar {3}$ m symmetry. The presence of two orientations for the coronene molecules related by an in‐plane 90° rotation (merohedral disorder) allows for fourfold symmetry along the <100> direction. The disorder has dynamic features because 2 H NMR spectroscopic studies revealed that the coronene molecules undergo an in‐plane flipping motion. The observation of two motional sites with significantly different rotational rates (300 Hz and 5 MHz at 103 K) in an approximate 2:1 ratio appears to be consistent with the splitting of a Raman‐active A 1g mode, confirming a random charge‐disproportionated state instead of a uniform partially‐charged state. The slower‐ and faster‐rotating species are assigned to charge‐rich and charge‐poor coronenes, respectively, with respect to C–H ··· Cl hydrogen bonds with neighboring Mo 6 Cl 14 2– cluster units. The electrical conductivity of the salt is rather high but is well‐described by a three‐dimensional (3D) variable‐range hopping mechanism, which is possibly associated with the random charge disproportionation. These results provide a significant step forward in developing an isotropic 3D π‐conducting system composed of planar π‐conjugated molecules.