Fullerene-carbene Lewis acid-base adducts.

Area of Science:

• Fullerenes chemistry
• Organometallic chemistry
• Materials science

Background:

• Fullerenes, such as C(60), are carbon allotropes with unique electronic properties.
• N-heterocyclic carbenes (NHCs) are versatile ligands and organic bases.
• Understanding fullerene doping is crucial for developing advanced electronic materials.

Purpose of the Study:

• To investigate the reaction between N-heterocyclic carbenes (NHCs) and C(60) fullerenes.
• To characterize the resulting adduct and its electronic properties.
• To explore the potential of this reaction for fullerene n-doping.

Main Methods:

• Synthesis of a zwitterionic adduct from NHC and C(60).
• UV-Vis spectroscopy to analyze absorption bands.
• UV photoelectron spectroscopy (UPS) to determine ionization potential.
• Density Functional Theory (DFT) calculations for electronic structure analysis.

Main Results:

• Formation of a thermally stable zwitterionic adduct via a C-C single bond.
• Observed low-energy absorption bands indicative of electron density transfer to C(60).
• Adduct showed a significantly lower ionization potential (∼1.5 eV) compared to pristine C(60).
• DFT calculations confirmed charge polarization within the C-C bond, with electron density delocalized onto the C(60) cage.

Conclusions:

• Fullerenes can act as Lewis acids, reacting with carbon-based Lewis bases like NHCs.
• The reaction results in n-doping of the fullerene core through C-C bond formation.
• This study provides a novel pathway for tuning fullerene electronic properties.