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Synthesis and Structural Characterization of Hexa‐ tert ‐butyl‐ hexa‐ peri ‐hexabenzocoronene, Its Radical Cation Salt and Its Tricarbonylchromium Complex
Author(s) -
Herwig Peter T.,
Enkelmann Volker,
Schmelz Oliver,
Müllen Klaus
Publication year - 2000
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/(sici)1521-3765(20000515)6:10<1834::aid-chem1834>3.0.co;2-l
Subject(s) - hexa , chemistry , anhydrous , medicinal chemistry , salt (chemistry) , radical ion , solubility , organic chemistry , ion
The hexa‐ tert‐ butyl substituted hexa‐ peri ‐hexabenzocoronene was synthesized in an overall yield of 83 % from 4‐ tert ‐butylphenylacetylene. The key step was the oxidative cyclodehydrogenation of hexa(4‐ tert ‐butylphenyl)benzene with anhydrous FeCl 3 in CH 2 Cl 2. The high solubility of hexa‐ tert ‐butyl‐hexa‐ peri ‐hexabenzocoronene in common organic solvents allowed a comprehensive spectroscopic characterization of this compound in solution. Electrochemical oxidation at −30 °C in the presence of tetrabutylammonium hexafluoroarsenate led to the formation of a stable radical cation salt. Reaction of hexa‐ tert ‐butyl‐hexa‐ peri ‐hexabenzocoronene with an excess of tricarbonyl(naphthalene)chromium in THF/dioxane afforded a mixture of mono‐ and bis‐tricarbonylchromium complexes which could be separated by chromatography. The molecular structures of the parent compound, its radical cation salt and its mono‐ tricarbonylchromium complex were determined by X‐ray analysis and discussed in detail. Remarkably, the crystal structures of these compounds are mainly dominated by the formation of dimers of the aromatic cores.