Nuclear Magnetic Resonance Investigations of Some Group v Metal Fluorides and Oxyions

The nuclear magnetic resonances of 51 V, 93 Nb, 121 Sb, 123 Sb, and 181 Ta in solutions of the pentafluorides of these elements were measured. All of these nuclei have large electric quadrupole moments. In most cases the chemical species observed was identified by spin-multiplet splitting of the metal resonance. In aqueous 48% HF solutions the 181 Ta resonance could not be observed; the 121 Sb and 123 Sb resonances consist of a symmetrical septet, corresponding to the hexafluoride ion; the 93 Nb resonance consists of a single exchange narrowed line; and the 5I V resonance consists of a symmetrical quintet, corresponding to the VOF 4 − ion. In alcohol solution NbF 5 disproportionates to form NbF 6 − , whereas in ether and triethylamine solutions, the complexes NbF 5 •OEt 2 and NbF 6 •NEt 3 are formed. The latter complexes were confirmed by proton resonance measurements. Resonances of 5I V in aqueous solutions of V 2 O 5 and of NH 4 VO 3 as a function of pH show a parallel behavior and reveal the presence of six different oxyions of vanadium. Five of these resonances are assigned to the species, VO 4 3− , VO 3 − , V 2 O 7 4− V 3 O 10 6− and VO 2 + , on the basis of the resonance line width and the pH range in which the resonance appears.