Isolation of kinetically-stabilised diarylchalcogenide radical cations

Area of Science:

• Inorganic Chemistry
• Materials Science
• Organic Chemistry

Background:

• Chalcogenide radical cations (e.g., [R₂E]^•+ for E=S, Se, Te) are vital but often transient intermediates.
• Sulfide radical cations are implicated in biological processes like oxidative stress and neuropathology.
• Previous work established meta-terphenyl-based dichalcogenide radical cations and a telluride analogue.

Purpose of the Study:

• To synthesize and characterize novel sulfur and selenium chalcogenide radical cations, completing a previously initiated series.
• To investigate the structural and electronic properties of these newly synthesized radical cations.
• To explore the potential for creating stable, isolable radical cation salts.

Main Methods:

• Single-electron oxidation of diarylchalcogenides (M^SFluindPhE) using xenon difluoride (XeF₂).
• Use of potassium tetrakis(pentafluorophenyl)borate (K[B(C₆F₅)₄]) as a counterion to isolate radical cation salts.
• Characterization techniques included electron paramagnetic resonance (EPR) spectroscopy, cyclic voltammetry, and optical absorption spectroscopy.
• Structural analysis via single-crystal X-ray diffraction for selenium and tellurium analogues.
• Computational analysis using quantum mechanical methods.

Main Results:

• Successfully synthesized and isolated deeply colored, stable radical cation salts: [M^SFluindPhE][B(C₆F₅)₄] for E = S, Se, Te.
• Elucidated the structural and electronic properties of the sulfur, selenium, and tellurium radical cations.
• Demonstrated the stability and isolability of these chalcogenide radical cations under ambient conditions.
• Provided comprehensive data through spectroscopic, electrochemical, crystallographic, and computational studies.

Conclusions:

• The synthesis of stable chalcogenide radical cations ([M^SFluindPhE]^•+) for sulfur, selenium, and tellurium has been achieved.
• These stable radical cations serve as valuable platforms for fundamental research into reactive intermediates.
• The findings contribute to the understanding of chalcogen chemistry and the development of novel functional materials.