Li6E5Li6: Tetrel Sandwich Complexes with 10‐π‐Electrons

• Published in: Angewandte Chemie International Edition Vol. 63; no. 5
• Main Authors: Inostroza, Diego, Leyva‐Parra, Luis, Pino‐Rios, Ricardo, Solar‐Encinas, José, Vásquez‐Espinal, Alejandro, Pan, Sudip, Merino, Gabriel, Yañez, Osvaldo, Tiznado, William
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 25.01.2024
• Edition: International ed. in English
• Subjects: Aromaticity; Bonding; Electrons; Flow stability; Global Minimum; Ring currents; Sandwich; Sandwich structures; Stability; Ten π-Electrons; Tetrel Chemistry
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.202317848

When (4n +2) π‐electrons are located in single planar ring, it conventionally qualifies as aromatic. According Hückel's rule, systems possessing ten π‐electrons should be aromatic. Herein we report a series of D5h Li6E5Li6 sandwich structures, representing the first global minima featuring ten π‐electrons E510− ring (E=Si−Pb). However, these π‐electrons localize as five π‐lone‐pairs rather than delocalized orbitals. The high symmetry structure achieved is a direct consequence of σ‐aromaticity, particularly favored in elements from Si to Pb, resulting in a pronounced diatropic ring current flow that contributes to the enhanced stability of these systems. We introduce a series of tetrel sandwich complexes characterized by ten π‐electrons ([Li6]5+[E5]10−[Li6]5+). These complexes are both thermochemically and kinetically stable and exhibit σ‐aromaticity.