Pressure effects on the two-site jumping of sodium and potassium cations in a 2,5-di-tert-butyl-1,4-benzoquinone ion pair have been studied using a high-pressure EPR technique. The rate constants of the intramolecular and intermolecular migrations for Na+ and K+ were determined from an EPR spectral simulation. The migration rates were found to be accelerated by increasing the external pressure. Using the pressure dependence of the migration rates, we estimated the activation volumes of the intramolecular (ΔV1‡) and intermolecular (ΔV2‡) processes for the Na+ and K+ migrations: ΔV1‡ = -5.3 cm3 mol-1 and ΔV2‡ = -29 cm3 mol-1 for Na+, and ΔV1‡ = -8.3 cm3 mol-1 and ΔV2‡ = -0.85 cm3 mol-1 for K+. Based on the results, the mechanisms for the two-site jumping of Na+ and K+ are discussed in terms of volume.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Organic Chemistry
- Inorganic Chemistry