Molybdenum(V) Species in Alkali Chloride Melts: An Electronic Absorption Spectroscopy Study

Abstract

Electronic absorption spectra of solutions of molybdenum pentachloride in fused alkali chlorides were studied between 450 and 850 oC. LiCl-KCl, NaCl-CsCl, NaCl-KCl-CsCl eutectics and NaCl-KCl equimolar mixture were used as solvents. Although the experimental spectra contain only one broad band in the visible region, resolving the spectra into overlapping bands revealed two individual components under the experimental band. The ratio of intensities of the constituent bands depends on temperature and they are attributed to the absorption of MoCl6 - ion and MoCl5 molecular species. Spectroscopic parameters of MoCl6 - were determined and MoCl6 -↔MoCl5 equilibrium is discussed. Absorption spectra of gaseous MoCl5 were also recorded.