Two-electron/24-center (2e/24c) bonding in novel diradical π-dimers

Area of Science:

• Supramolecular Chemistry
• Computational Chemistry
• Materials Science

Background:

• The phenalenyl (PLY) π-dimer is known for its two-electron/twelve-center (2e/12c) π-π bonding.
• Understanding π-π interactions is crucial for designing novel molecular materials and understanding electronic properties.

Purpose of the Study:

• To design and investigate a series of novel diradical π-dimers with enhanced two-electron/multicenter (2e/mc) π-π bonding.
• To explore the characteristics of pancake-shaped 2e/24c π-π bonding in these new systems.
• To provide new insights into the unique features of 2e/mc π-π bonding.

Main Methods:

• Design and theoretical investigation of diradical π-dimers.
• Analysis of Wiberg bond index (WBI) to determine the position of maximum inter-radical interaction.
• Quantitative analysis of interaction energy contributions using energy decomposition analysis (EDA).

Main Results:

• A series of diradical π-dimers with pancake-shaped 2e/24c π-π bonding character were successfully designed.
• The Wiberg bond index identified the strongest interaction points between the radical layers.
• Diradical π-dimer 2180 exhibited the smallest layer distance and the most significant inter-layer radical interaction.

Conclusions:

• The designed diradical π-dimers demonstrate novel 2e/24c π-π bonding characteristics.
• These findings offer a deeper understanding of the nature and strength of multicenter π-π interactions.
• The study provides a foundation for exploring unusual PLY analogues and their unique bonding features.