11B and 10B NMR Investigations in Aqueous Solutions

B NMR chemical shifts and linewidths have been measured in very dilute aqueous solutions of boric acid and borates. The results can be explained bv taking pH dependent weighted averages over the species B(OH) and B(OH) . The B− B primary isotope effect on the magnetic shielding is smaller then 3 · 10 . The H O - D O solvent isotope effect on T has been established for B and B in the species mentioned, and from the ratios of T the quadrupolar origin of the relaxation mechanism has been inferred.