An electron spin resonance study of metal ion separations in dimeric vanadyl (DL)- and (DD)-tartrates

The e.s.r. spectra of frozen aqueous solutions containing vanadyl (DL)- and (DD)-tartrates are consistent with the formation of dimeric species. Computer simulation of the spectra, assuming a monoclinic dimer model, has enabled the determination of the magnetic parameters associated with vanadyl ions, the internuclear separations between the metal ions in the dimers and their relative orientation. For vanadyl (DL)-tartrate dimer, the excellent agreement between structural parameters for the solid and frozen glass was taken to indicate that the same structure exists in both states. In the case of vanadyl(DD)-tartrate, however, although the overall symmetry is maintained, a slight reduction in the vanadyl vanadyl separation is believed to occur as a result of incorporation into an ethylene glycol-water glass.