SiIV incorporation into a [28]hexaphyrin that triggered formation of Möbius aromatic molecules.
Incorporation of Si(IV) into an expanded porphyrin has been achieved for the first time. Treatment of [28]hexaphyrin 1 with CH(3)SiCl(3) and N,N-diisopropylethylamine gave Si(IV) complex 2 and its N-fused product 4 that both have Möbius aromatic nature. In both complexes, the coordinated Si atom is satisfied in a typical trigonal bipyramidal coordination. Si(IV) incorporation induces conformational rigidification and redshifted absorption profiles due to σ-π conjugation between the Si atom and hexaphyrin macrocycle. Tamao-Fleming oxidation of 2 with H(2)O(2) gave β-hydroxy [28]hexaphyrin 5, which exists as a ruffled rectangular shape in the solid state, yet it has been revealed to exist predominantly as a twisted Möbius aromatic conformer in CH(2)Cl(2).
Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku Kyoto, 606-8502 (Japan), Fax: (+81) 75-753-3970.
Shin-ichiro
S
Ishida
Takayuki
T
Tanaka
Jong Min
JM
Lim
Dongho
D
Kim
Atsuhiro
A
Osuka
Möbius aromaticity; Tamao-Fleming oxidation; aromaticity; hexaphyrins; silicon