Möbius Aromatic [28]Hexaphyrin Germanium(IV) and Tin(IV) Complexes: Efficient Formation of Triplet Excited States

Abstract

[28]Hexaphyrin GeIV and SnIV complexes were synthesized in high yields by reactions of [28]hexaphyrin with GeCl4 or SnCl4 in the presence of triethylamine. Both complexes display distinct 28π Möbius aromatic character and possess a trigonal bipyramidal geometry at the central GeIV or SnIV atom. The equatorial hydroxy group of the GeIV complex was smoothly exchanged with neutral nucleophiles, such as phenol derivatives and thiophenol, with retention of configuration. In the SnIV complex, intersystem crossing to the T1 state is remarkably enhanced owing to the effective heavy‐atom effect, thus allowing the formation of the T1 state in high yield. The T1 states of the GeIV and SnVI complexes were found to be antiaromatic on the basis of the transient absorption features in line with the Baird rule.

Resolution of Expanded Porphyrinoids: A Path to Persistent Chirality and Appealing Chiroptical Properties

“…Incorporation of a Ge IV ion into 10 led to rigidification of the twisted Möbius structure, giving rise to the [28]hexaphyrin complex 10‐Ge (Figure 10). [28] Complex 10‐Ge displays a trigonal‐bipyramidal coordination geometry about the Ge IV center with a hydroxyl group serving as an equatorial ligand. This hydroxyl can readily be exchanged with a neutral nucleophile, such as 4‐methoxyphenol, to produce a product 10‐Ge‐OAr with a general structure that retained the configuration of 10‐Ge .…”

Synthesis of (bis)Silicon Complexes of [38], [37], and [36]Octaphyrins: Aromaticity Switch and Stable Radical Cation

“…[1] Expanded porphyrins have served as effective platforms to realize Mçbius aromatic and antiaromatic networks. [3][4][5][6][7] As an important example,t he [40]octaphyrin bis(P V )c omplex A was reported as an expanded isophlorin, [4a] in which the two electron-withdrawing P V moieties help to twist the p-electronic network and stabilize the highly reduced ligand with 40p-electron systems ( Figure 1). [3][4][5][6][7] As an important example,t he [40]octaphyrin bis(P V )c omplex A was reported as an expanded isophlorin, [4a] in which the two electron-withdrawing P V moieties help to twist the p-electronic network and stabilize the highly reduced ligand with 40p-electron systems ( Figure 1).…”

“…a) Absorption spectral changes on titration experiments upon additiono fF cPF6 to the solution of 2 in dry CH 2 Cl 2 .b )ESR spectrum of 4 in CH 2 Cl 2 /acetone/toluene at 50 K. c) Calculated spin density (isovalue:0 .0008).Scheme 2. Synthesis of the radical cation 4. meso-Pentafluorophenyl groups are omitted for clarity.…”

“…[2] Recently,i ncorporation of main-group elements,s uch as B, P, Si, Ge,a nd Sn, into expanded porphyrins has emerged as an effective strategy to explore novel macrocycles with intriguing properties. [3][4][5][6][7] As an important example,t he [40]octaphyrin bis(P V )c omplex A was reported as an expanded isophlorin, [4a] in which the two electron-withdrawing P V moieties help to twist the p-electronic network and stabilize the highly reduced ligand with 40p-electron systems (Figure 1). These features also can be seen in Mçbius antiaromatic [30]hexaphyrin bis(P V )complexes.…”