Incorporation of SiIV into an expanded porphyrin has been achieved for the first time. Treatment of hexaphyrin 1 with CH 3SiCl3 and N,N-diisopropylethylamine gave SiIV 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. SiIV 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 H2O2 gave β-hydroxy 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 CH2Cl2.
All Science Journal Classification (ASJC) codes
- Organic Chemistry