Hexaphyrin Ge IV and Sn IV complexes were synthesized in high yields by reactions of hexaphyrin with GeCl 4 or SnCl 4 in the presence of triethylamine. Both complexes display distinct 28π Möbius aromatic character and possess a trigonal bipyramidal geometry at the central Ge IV or Sn IV atom. The equatorial hydroxy group of the Ge IV complex was smoothly exchanged with neutral nucleophiles, such as phenol derivatives and thiophenol, with retention of configuration. In the Sn IV complex, intersystem crossing to the T 1 state is remarkably enhanced owing to the effective heavy-atom effect, thus allowing the formation of the T 1 state in high yield. The T 1 states of the Ge IV and Sn VI complexes were found to be antiaromatic on the basis of the transient absorption features in line with the Baird rule.
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