A carregar...
Publicação
Tris(pyrazolyl)methane molybdenum tricarbonyl complexes as catalyst precursors for olefin epoxidation
| Nome: | Descrição: | Tamanho: | Formato: | |
|---|---|---|---|---|
| 1.49 MB | Adobe PDF |
Orientador(es)
Resumo(s)
The molybdenum tricarbonyl complexes [Mo(CO)3(HC(3,5-Me2pz)3)] (1) and [Mo(CO)3(HC(pz)3)]
(2)(HC(3,5-Me2pz)3 = tris(3,5-dimethyl-1-pyrazolyl)methane, HC(pz)3 = tris(1-pyrazolyl)methane) were
obtained in good yields by the microwave-assisted reaction of Mo(CO)6 with the respective
organic ligand. Complete oxidative decarbonylation of 1 and 2 was achieved by reaction
with excess tert-butylhydroperoxide (TBHP) in 1,2-dichloroethane at 55 ◦C. For complex 1, the
(2-oxo)bis[dioxomolybdenum(VI)] hexamolybdate of composition [{MoO2(HC(3,5-Me2pz)3)}2(2-
O)][Mo6O19] (3) was obtained in good yield, and its structure was determined by single crystal X-ray
diffraction. The compound (4) obtained by oxidative decarbonylation of 2 was not unambiguously identified,
but may be chemically analogous to 3. Compounds 1–4 were examined for the first time as
homogeneous (pre)catalysts for the epoxidation of olefins with TBHP, using different types of cosolvents
at 55 ◦C. During the catalytic reactions 1 and 2 transform in situ into 3 and 4, respectively, and the
latter two are fairly stable catalysts. Catalytic tests and characterization studies of the recovered catalysts
were carried out in an attempt to understand the kinetic differences observed between the compounds
prepared in situ during the catalytic reaction and those prepared prior to the catalytic reaction, from the
same precursor complex.
Descrição
Palavras-chave
Molybdenum Tris(pyrazolyl)methane ligands Homogeneous catalysis Olefin epoxidation Oxidative decarbonylation
Contexto Educativo
Citação
Gomes, A.C.; Neves, P.; Figueiredo, S.; Fernandes, J.A.; Valente, A.A.; Almeida Paz, F.A.; Pillinger, M.; Lopes, A.D.; Gonçalves, I.S.Tris(pyrazolyl)methane molybdenum tricarbonyl complexes as catalyst precursors for olefin epoxidation, Journal of Molecular Catalysis A: Chemical, 370, s/n, 64-76, 2013.
Editora
Elsevier