Isotope effects in the nuclear magnetic resonance spectra of mixed aqua complexes of AlIII

Abstract

Aluminium-27 n.m.r. measurements of the isotope shifts caused by the substitution of hydrogen by deuterium in the water ligands of the hydrate complexes [Al(H₂O)₅SO₄]⁺ and {Al(H₂O)_n[OPMe(OMe)₂]_6–n}³⁺, 0 ⩽n⩽ 6, are reported in an investigation of whether such shifts can be safely used to determine extents of preferential solvation. It is shown that in the case of the phosphonate series, the variation of shift with n is essentially linear but that of the isotope shift is not. The implications of this for earlier work are discussed.