IR Emission Spectra and Electronic Absorption Spectra of Solutions of Na_2WO_4 and Na_nWO_3F_3 (n = 3, 4) in Molten Alkali-Metal Halides

摘要

The electronic and IR spectra of molten systems NaCl-CsCl-NaF-Na_2WO_4, KBr-NaF-Na_2WO_4, NaCl-CsCl-NaF-Na_nWO_3F_3, and KBr-NaF-Na_nWO_3F_3 (n = 3,4) were measured. It was found that, depending on oxidation/reduction conditions, penta- and hexavalent tungsten oxyfluoride complexes-WO_3F~-, WO_3F_2~(2-) , WO_3F_2~(3-), WO_3F_3~(3-) and WO_3F_2~(4-), -are formed in all molten mixtures. The coordination number and composition of the coordination sphere of these complexes depend on the molar ratio delta = F/W.