2.6 Author:
   Dove, Michael F. A.; Sanders, Jeremy C. P.; Appelman, Evan H.
Reference:
   Journal, MRCHEG, Magn.Reson.Chem., EN, 33, 1, 1995, 44-58
Title:
   Comparative Multinuclear (35Cl, 79Br, 81Br, 127I and 17O) Magnetic Resonance Study of the Perhalate Anions XO4(-) (X = Cl, Br or I) in Acetonitrile Solution
Abstract:
The NMR spectra (35Cl, 79Br, 81Br, 127I and 17O) of the tetrahedral perhalate anions XO4(-) (X = Cl, Br and I) were compared for the first time in acetonitrile solution, a medium in which the resonances are relatively sharp and in which no oxygen exchange occurs.Relaxation studies of the quadrupolar nuclei in these solutions at 24 deg C are reported and show that excellent spectra may be obtained at 0.1 M concentration; thus the observation of separate resonances for Cl(16)O4(-) and Cl(18)O(16)O3(-) represents the first reported instance of a 35Cl secondary isotopic shift <1D(35)Cl((18,16)O) = -0.090 ppm>.Enrichment with 17O of all three ions was carried out and the 1J(127I,17O) coupling constant (489 Hz) has been observed for the first time.The chemical shifts and coupling constants are discussed, especially in connection with the anomalous properties of the perbromate ion.Halogen chemical shifts for BrO3F, IF7 and IF6(+)AsF6(-) are reported for the first time.