The flash photolysis of di‐μ‐oxo‐bis(oxo‐molybdate(V)) acid aqueous solutions in the presence of excess thiocyanate

Abstract

The flash photolysis of the mono and di-thiocyanate complexes of @-ox0 bis(oxomolybdenum(V)) ( M O~O~( N C S ) , ( H~O )~_~~~~" where x = 1,2) has been studied in the system composed of perchloric acid solutions of M O~O~( H~O )~~~ 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 p-0x0-bis (0x0-molybdenum(V)) species: Mo203( HZO): ' (A), Mo203(NCS) (H20):' ( B ) , and M O~O~( N C S )~( H~O )~~' (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(V1) and Hz.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.

Efficient recyclable catalytic system for deoxygenation of sulfoxides: catalysis of ionic liquid-molybdenum complexes in ionic liquid solution

“…4e) that can be related to [Mo 2 O 3 (NCS) 8 ] 4À species according to the literature. [45][46][47] The purple solid showed a single IR absorption band at 945 cm À1 , attributed to one oxo group, and a band at 750 cm À1 which can be assigned as vibration of linear Mo-O-Mo unit. 48,49 Based on Arzoumanian et al reports, 50,51 a mechanism could be proposed with Mo(V) complex as an intermediate for the oxo-transfer process (Scheme 2).…”

Reacciones fotoquímicas y catalíticas en las que participan complejos de Mo₂O₄²⁺ en presencia de haluros en medio ácido

“…En nuestro laboratorio, desde hace algún tiempo, se ha encausado el estudio sistemático de reacciones fotoinducidas de compuestos de coordinación de Mo(V) en soluciones ácidas acuosas y no acuosas (13) (15) (16).…”

“…Mo2O3(NCS)(H2O)73+ y Mo2O3(NCS)2(H2O)62+ entre las que se establece un equilibrio antes de observar un decaimiento que corresponde a una cinética de primer orden. En este sistema el comportamiento observado también puede atribuirse al intermediario Mθ2O3(H2O)84+ cuyo decaimiento conduce a los mismos productos de reacción ya mencionados con anterioridad (15).…”

“…293 K) = 1,54 . 10'3 moles (15) Conociendo la concentración de H2 y el número total de moles en la fase gaseosa, el número de moles de hidrógeno resulta:…”