The flash photolysis of di-μ-oxo-bis(oxo-molybdate(V)) acid aqueous solutions in the presence of excess thiocyanate
✍ Scribed by D. O. Martire; M. C. González; M. R. Feliz; L. Cafferata; A. L. Capparelli
- Publisher
- John Wiley and Sons
- Year
- 1991
- Tongue
- English
- Weight
- 804 KB
- Volume
- 23
- Category
- Article
- ISSN
- 0538-8066
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✦ Synopsis
Abstract
The flash photolysis of the mono and di‐thiocyanate complexes of μ‐oxo bis(oxo‐molybdenum(V)) (Mo~2~O~4~(NCS)~x~(H~2~O)~6−x~^(2−x)+^ where x = 1, 2) has been studied in the system composed of perchloric acid solutions of Mo~2~O~4~(H~2~O)~6~^2+^ in the presence of excess thiocyanate.
Irradiation with light in the wavelength range 250–340 nm induced the formation of three reaction intermediates identified as μ‐oxo‐bis (oxo‐molybdenum(V)) species: Mo~2~O~3~(H~2~O)~8~^4+^ (A), Mo~2~O~3~(NCS) (H~2~O)~7~^3+^ (B), and Mo~2~O~3~(NCS)~2~(H~2~O)~6~^2+^ (C). A rapid equilibria between the transient species is established before they decay following a first order kinetics. Intermediate A is the only species effective in promoting the observed decay leading to the end products Mo(VI) and H~2~.
The relative absorption spectrum of species A, B, and C are reported, as well as the measured stability constants for the formation of B and C in the temperature range 20–45°C. An overall mechanism is proposed.