Solvents Promote Selective TEDA^2+. Formation Driven through a Pnicogen Bond in Selectfluor

Area of Science:

• Organic chemistry
• Spectroscopy
• Computational chemistry

Background:

• Selectfluor is a widely used electrophilic fluorinating agent.
• Understanding its reactivity in different solvent environments is crucial for synthetic applications.
• The potential for radical formation from Selectfluor has not been previously explored.

Purpose of the Study:

• To investigate the formation of radical species from Selectfluor in electron-rich solvents.
• To elucidate the mechanism of radical formation.
• To quantify the interaction between Selectfluor and solvents.

Main Methods:

• Electron Paramagnetic Resonance (EPR) spectroscopy to detect radical species.
• ¹⁹F Nuclear Magnetic Resonance (NMR) spectroscopy to determine association constants.
• Density Functional Theory (DFT) calculations to model interactions.

Main Results:

• Evidence for spontaneous formation of the TEDA²⁺ radical from Selectfluor in DMF, acetonitrile, and acetone.
• Determination of association constants for Selectfluor in these solvents.
• Identification of a pnicogen bond interaction between Selectfluor and solvent molecules via DFT.

Conclusions:

• The pnicogen bond interaction between Selectfluor and electron-rich solvents is proposed as the initial step in TEDA²⁺ radical formation.
• This finding sheds light on the reactivity of Selectfluor and potential side reactions in solution.
• The study provides a new mechanistic pathway for radical generation involving fluorinating agents.