NMR and ESR Studies of Solvation and Complex Formation In Aqueous and Non-Aqueous Solutions of Paramagnetic Ions

摘要

The objectives of the present research project were to study the effect of complex formation on the properties of the solvation shell and the electronic relaxation. The research was centered on solutions of Fe(3+), Cr(3+) and Mn(2+). It was shown by ESR measurements at X- and Q-band frequencies that the electronic relaxation in solutions of these ions is due to modulation of the quadratic zero field splitting (Z.F.S.) interaction. A theory was suggested in which the Z.F.S. and its time modulation result from collisions between solvent molecules and the solvated ions. Expressions were derived for electron and nuclear relaxation in solutions of such ions and compared with results from NMR measurements. The effect of complex formation on the ESR and NMR of Fe(3+) and Cr(3+) were studied and interpreted using the above theory and parameters for the collision rate and Z.F.S. interaction were determined. The project also included an NMR study of solutions of Cu(2+) ions in methanol and nuclear relaxation measurements of alkali metal ions in aqueous solutions containing paramagnetic salts. (Author)