17O and1H chemical shifts of water in solutions of some ammonium salts: evaluation of the anionic effect on the17O and1H chemical shifts of water in aqueous solutions of mineral acids

Authors:
  • VMVahur Mäemets
    Vahur Mäemets
  • IKIlmar Koppel
    Ilmar Koppel
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Abstract
In this paper the 1H chemical shifts δ(1Hav) and the water 17O chemical shifts δ(17OH2) in aqueous solutions of NH4Cl, NH4Br, NH4I, NH4NO3, NH4ClO4, (NH4)2SO4, NH4H2HPO4 and (NH4)2HPO4 are presented and discussed. For δ(17OH2), values shift towards higher frequencies, relative to pure water δ(17OH2). NH4NO3 and NH4ClO4 change the water oxygen chemical shift value only slightly as compared with the other solutes. Both positive and negative δ(1Hav) values relative to pure water as an external reference were observed. The strong contribution of the conjugate base anion of the acids to the measured 17O and 1H chemical shift values of water was found. Using the ammonium ion as standard, the anionic effect on these parameters was estimated and subtracted from the measured δ(17OH2) and δ(1Hav) values for the aqueous solutions of these acids.

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