Spectroscopic evidence for selenium(IV) dimerization in aqueous solution

The aqueous speciation of selenium(IV) was elucidated by a combined approach applying quantum chemical calculations, infrared (IR), Raman, and 77Se NMR spectroscopy. The dimerization of hydrogen selenite (HSeO3−) was confirmed at concentrations above 10 mmol L–1 by both IR and NMR spectroscopy. Quantum chemical calculations provided the assignment of vibrational bands observed to specific molecule modes of the (HSeO3)22– ion. The results presented will provide a better understanding of the chemistry of aqueous Se(IV) which is of particular interest for processes occurring at mineral/water interfaces.