Pyrazine-bridged molybdenum(0) carbonyl and molybdenum(VI) oxide network solids as catalysts for epoxidation and sulfoxidation

• Autor(a) principal: Gomes, Diana M.
• Data de Publicação: 2023
• Outros Autores: Silva, Andreia F., Gomes, Ana C., Neves, Patrícia, Valente, Anabela A., Gonçalves, Isabel S., Pillinger, Martyn
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10773/40126

The horizons of epoxidation and sulfoxidation processes may be expanded by developing new, efficient, and versatile catalysts. In the present work, three pyrazine-bridged molybdenum(0/VI)-based coordination network solids have been investigated for the epoxidation of olefins and the oxidation of sulfides. The materials studied were the Mo0-based metal-organic framework (MOF) fac-Mo(CO)3(pyz)3/2·1/2pyz (1) with a structure consisting of stacked fac-Mo(CO)3(pyz)3/2 coordination layers, the cubic phase fac-Mo(CO)3(pyz)3/2 (2) with a dense framework consisting of two interpenetrating coordination networks, and the molybdenum oxide-pyrazine hybrid material [Mo2O6(pyz)] (3) with a structure consisting of perovskite-like MoO3 layers pillared by pyz molecules. In the model reaction of cis-cyclooctene with tert-butyl hydroperoxide (TBHP) at 70 °C, quantitative yields of the epoxide were obtained within 2 h for 1, 4 h for 2, and 24 h for 3. Catalysts 1-3 were further examined for the epoxidation of other olefins, including the bio-olefins dl-limonene, methyl oleate and methyl linoleate, and the reaction scope was expanded to include the oxidation of sulfides. In the reactions of the bio-olefins, 3 was highly selective, giving only diepoxide and/or monoepoxide products. While the tricarbonyl-pyrazine-molybdenum(0) compounds displayed higher activity, by-products were obtained in the reactions of dl-limonene and methyl linoleate, namely limonene-1,2-diol and hydroxytetrahydrofuran cyclization products, respectively. Catalysts 1-3 displayed high activity for the selective oxidation of sulfides (methyl phenyl sulfide and diphenyl sulfide) to sulfones under mild conditions (35 °C).