The flash photolysis of pyridinium di-μ-oxo-bis(oxo tris (isothiocyanate) molybdate(V)) in ethyl acetate

• Published in: Journal of photochemistry and photobiology. A, Chemistry. Chemistry., 1992-08, Vol.67 (3), p.267-277
• Main Authors: González, M.C., Feliz, M.R., Capparelli, A.L.
• Format: Article
• Language: English
• Subjects: Chemistry; Exact sciences and technology; General and physical chemistry; Photochemistry; Physical chemistry of induced reactions (with radiations, particles and ultrasonics)
• ISSN: 1010-6030; 1873-2666
• DOI: 10.1016/1010-6030(92)87001-P

The flash photolysis of pyridinium di-μ-oxo-bis (oxo tris (isothiocyanate) molybdate(V)), ((PyrH)4MoV2O2 (μ-O)2(NCS)6) in ethyl acetate has been carried out in the temperature range 20–41 °C under a nitrogen atmosphere. Irradiation with light in the range 280–340 nm induces the formation of an intermediate, with an absorption maximum around 520 nm, which decays following a first order law in the millisecond time range. The measured activation energy is Ea = 61±5 kJ mol−1. The observed intermediate was identified as a μ-oxo-bis (oxo-isothiocyanate) molybdate(V) species, thus suggesting that the photolysis of (PyrH)4MoV2O2(μ-O)2(NCS)6 induces a partial bridge opening without change in the oxidation state of molybdenum. The chemical process observed in the millisecond species, leading to H2 and MoVI as final products. Both the nature of the intermediate and its decomposition reactions are discussed in the light of the observed experimental facts and the evidence presented in the literature,