Supramolecular trapping of a cationic all-metal σ-aromatic {Bi4} ring.
Nat Chem
; 16(9): 1523-1530, 2024 Sep.
Article
in En
| MEDLINE
| ID: mdl-38760432
ABSTRACT
Aromaticity in organic molecules is well defined, but its role in metal-only rings remains controversial. Here we introduce a supramolecular stabilization approach of a cationic {Bi4} rhomboid within the symmetric charge sphere of two bowl-shaped dianionic calix[4]pyrrolato indinates. Crystallographic and spectroscopic characterization, quantum chemical analysis and magnetically induced ring currents indicate σ-aromaticity in the formally tetracationic 16-valence electron [Bi4]4+ ring. Computational screening for other p-block elements identifies the planar rhomboid as the globally preferred structure for 16-valence electron four-atomic clusters. The aromatic [Bi4]4+ is isoelectronic to the [Al4]4-, a motif previously observed as antiaromatic in Li3[Al4]- in the gas phase. Thus, subtle factors such as charge isotropy seem to decide over aromaticity or antiaromaticity, advising for caution in debates based on the Hückel model-a concept valid for second-row elements but less deterministic for the heavier congeners.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Language:
En
Journal:
Nat Chem
/
Nat. chem. (Online)
/
Nature chemistry (Online)
Journal subject:
QUIMICA
Year:
2024
Document type:
Article
Affiliation country:
Country of publication: