Structural Studies Provide Insight on the Fate of 1,5-Dithiacanes: Two Electron Reversible Oxidation versus...

Area of Science:

• Organic Chemistry
• Electrochemistry
• Computational Chemistry

Background:

• 1,5-dithiocanes are cyclic organic compounds containing sulfur atoms.
• Understanding their oxidation mechanisms is crucial for developing new materials and catalysts.
• Conformational constraints can significantly influence chemical properties.

Purpose of the Study:

• To synthesize and characterize a conformationally constrained 1,5-dithiocane, norbornane-fused 1,5-dithiocane (norDTCO).
• To investigate the electronic structure and oxidation mechanism of norDTCO using Density Functional Theory (DFT) calculations.
• To correlate DFT predictions with experimental electrochemical data.

Main Methods:

• Synthesis of norbornane-fused 1,5-dithiocane (norDTCO).
• Density Functional Theory (DFT) calculations for neutral, radical cation, and dication states.
• Electrochemical studies (cyclic voltammetry) in acetonitrile and dichloromethane.

Main Results:

• DFT calculations predicted 2-center-3-electron bonding in the norDTCO radical cation and a transannular S-S sigma bond in the dication.
• Electrochemical oxidation in acetonitrile showed a nearly reversible two-electron wave, consistent with S-S sigma bond formation.
• Electrochemical oxidation in dichloromethane revealed two one-electron waves, indicating the absence of S-S sigma bond formation in this solvent.

Conclusions:

• The conformational constraint in norDTCO significantly influences its oxidation mechanism and the stability of oxidized species.
• Solvent choice plays a critical role in the electrochemical behavior of norDTCO, affecting transannular S-S bond formation.
• DFT calculations are valuable tools for predicting and understanding the electronic properties and reaction pathways of complex sulfur-containing molecules.