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Synthesis of (bis)Silicon Complexes of [38], [37], and [36]Octaphyrins: Aromaticity Switch and Stable Radical Cation
Author(s) -
Ishida Shinichiro,
Kim Jinseok,
Shimizu Daiki,
Kim Dongho,
Osuka Atsuhiro
Publication year - 2018
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.201801986
Subject(s) - antiaromaticity , chemistry , silicon , aromaticity , conjugated system , hexafluorophosphate , trigonal bipyramidal molecular geometry , oxidation state , photochemistry , medicinal chemistry , crystallography , organic chemistry , crystal structure , catalysis , molecule , polymer , ionic liquid
Silicon complexation of a [38]octaphyrin ( 1 ) was accomplished by reaction with an excess amount of MeSiCl 3 in the presence of N , N ‐diisopropylethylamine, thus giving an aromatic [38]octaphyrin bis(silicon) complex 2 . This complex was interconvertible with an antiaromatic [36]octaphyrin congener ( 3 ) by oxidation with MnO 2 and reduction with NaBH 4 . Curiously, mild oxidation of 2 with ferrocenium hexafluorophosphate afforded a [37]octaphyrin bis(silicon) complex 4 as an stable radical cation that can be stored under ambient conditions in the solid state. Owing to the two NNNCC‐five‐coordinated Si atoms bearing trigonal bipyramidal geometry, these octaphyrin bis(silicon) complexes take on similar and rigid figure‐of‐eight structures with different consecutive numbers of conjugated π‐electrons (38, 37, and 36), and are all stable.