The Hydration of Vanadyl Doped into Magnesium Acetate: Single Crystal Proton ENDOR at 20 K

The single crystal ESR and proton ENDOR of VO²⁺ doped into magnesium acetate tetrahydrate have been studied at 20 K. The VO²⁺ ion occupies Mg²⁺ sites, replacing Mg²⁺ together with one water molecule. Hyperfine tensors for the six protons in the three coordinating water molecules have been determined and their dipolar components used to construct a model of the proton geometry. The relation of the structure to that of {VO(H₂O)₅}²⁺ in a Tutton salt and in frozen aqueous solutions of vanadyl sulphate is discussed.