Molybdenum chemistry in molten LiCl-KCl eutectic: an electrochemical and absorption spectroscopy study of the concentration dependent stability of solutions of K3MoCl6 / Gabriel JC,Vincent D,Bouteillon J,Poignet JC,Volkovich VA,Griffiths TR // ELECTROCHIMICA ACTA. - 1999. - V. 44, l. 25. - P. 4619-4629.

ISSN/EISSN:

0013-4686 / 1873-3859

Type:

Article

Abstract:

The chemical behaviour of LiCl-KCl-K3MoCl6 solutions between 400 and 500 degrees C was investigated. They underwent slow decomposition, according to a concentration dependent disproportionation reaction yielding metallic molybdenum and a volatile black higher valency molybdenum compound, which corresponded with MoCl5, Chronopotentiometric determinations showed a single 3-electron reduction, yielding Mo. The process was slow with diffusion-controlled mass transfer. The concentration of the Mo(III) species, presumed in the form of MoC63- ions, was determined using linear sweep voltametry and open circuit voltage measurements and the overall Mo(III) species concentration by chemical analysis. The results showed MoC63- to be the predominant species in the melt and the presence of a previously proposed dinuclear species, Mo2Cl93-, could not be confirmed electrochemically. This arose to quantification errors in the determination of the electroactive species MoCl63- due to inherent problems in estimating the active surface area of the electrode. The electronic absorption spectrum of MoCl63- in LiCl-KCl eutectic at 400 degrees C is reported for the first time. Measurements were made above and below 0.045 mol dm(-3) K3MoCl6, the concentration above which the disproportionation reaction was relatively slow. The results are discussed in detail and the spectroscopic parameters of the octahedral MoC63- complex were calculated as: Dq = 1775 cm(-1), B = 511 cm(-1) and C = 1913 cm(-1). Although an additional band, at 340 nm, appeared during disproportionation it could not be identified with any currently known polynuclear molybdenum chloro complex or oxychloro complex. It is probably associated with an intermediate in the disproportionation process. No spectral evidence was thus obtained in support of the formation of dinuclear molybdenum species. (C) 1999 Elsevier Science Ltd. All rights reserved.

Author keywords:

molybdenum; molten chlorides; electrochemistry; spectroscopy; potassium hexachloromolybdate(III) METALS; SALTS

DOI:

10.1016/S0013-4686(99)00176-0

Web of Science ID:

ISI:000082555200016

Соавторы в МНС:

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Другие поля

Поле	Значение
Publisher	PERGAMON-ELSEVIER SCIENCE LTD
Address	THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND
Language	English
EISSN	1873-3859
Keywords-Plus	METALS; SALTS
Research-Areas	Electrochemistry
Web-of-Science-Categories	Electrochemistry
Author-Email	t.r.griffiths@chem.leeds.ac.uk
ResearcherID-Numbers	Volkovich, Vladimir/K-8339-2012
ORCID-Numbers	Volkovich, Vladimir/0000-0003-4438-1194
Number-of-Cited-References	19
Usage-Count-Last-180-days	1
Usage-Count-Since-2013	20
Journal-ISO	Electrochim. Acta
Doc-Delivery-Number	235QZ