LINE BROADENING OF PROTON MAGNETIC RESONANCE OF NONAQUEOUS SOLVENTS BY VANADYL ION

The solvent proton line broadening caused by solvated vanadyl ion has been measured in the solvents acetonitrile, dimethyl sulfoxide, trimethyl phosphate, and trimethyl phosphite. Chemical exchange control of the line broadening was observed only in acetonitrile, from which kex = 2.8g × 10s sec-1 (25°, assuming four exchanging solvent molecules in the coordination sphere of the vanadyl ion), ΔH‡ = 7.05 kcal mol-1, and Δ5‡ = -20 cal mol-1 deg-1. Comparison of the calculated and observed dipolar broadening indicates that only a lower limit can be placed on the exchange rates of dimethyl sulfoxide and trimethyl phosphate while an upper limit is obtained for the trimethyl phosphite system. © 1969, American Chemical Society. All rights reserved.