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Crystal Structure Determination of the Pentagonal‐Pyramidal Hexamethylbenzene Dication C 6 (CH 3 ) 6 2+
Author(s) -
Malischewski Moritz,
Seppelt K.
Publication year - 2017
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201608795
Subject(s) - hexamethylbenzene , dication , crystallography , crystal structure , chemistry , crystal (programming language) , materials science , molecule , benzene , organic chemistry , computer science , programming language
Abstract In contrast to the well‐known 2‐norbornyl cation, the structure of which was a matter of long debate until its pentacoordinated nature was recently proven by an X‐ray structure, the pentagonal‐pyramidal dication of hexamethylbenzene has received considerably less attention. This species was first prepared by Hogeveen in 1973 at low temperatures in magic acid (HSO 3 F/SbF 5 ), for which he proposed a non‐classical structure (containing a hexacoordinated carbon) based on NMR spectroscopy and reactivity studies, but no X‐ray crystal structure has been reported. C 6 (CH 3 ) 6 2+ can be obtained through the dissolution of hexamethyl Dewar benzene epoxide in HSO 3 F/SbF 5 and crystallized as the SbF 6 − salt upon addition of excess anhydrous hydrogen fluoride. The crystal structure of C 6 (CH 3 ) 6 2+ (SbF 6 − ) 2 ⋅HSO 3 F confirms the pentagonal pyramidal structure of the dication. The apical carbon is bound to one methyl group (distance 1.479(3) Å) and to the five basal carbon atoms (distances 1.694(2)–1.715(3) Å).