Synthesis, structure, and catalytic performance in cyclooctene epoxidation of a molybdenum oxide/bipyridine hybrid material: {[MoO3(bipy)][MoO3(H2O)]}n.
The reaction of [MoO(2)Cl(2)(bipy)] (1) (bipy = 2,2'-bipyridine) with water in a Teflon-lined stainless steel autoclave (100 degrees C, 19 h), in an open reflux system with oil bath heating (12 h) or in a microwave synthesis system (120 degrees C, 4 h), gave the molybdenum oxide/bipyridine hybrid material {[MoO(3)(bipy)][MoO(3)(H(2)O)]}(n) (2) as a microcrystalline powder in yields of 72-92%. The crystal structure of 2 determined from synchrotron X-ray powder diffraction data is composed of two distinct neutral one-dimensional polymers: an organic-inorganic polymer, [MoO(3)(bipy)](n), and a purely inorganic chain, [MoO(3)(H(2)O)](n), which are interconnected by O-H...O hydrogen bonding interactions. Compound 2 is a moderately active, stable, and selective catalyst for the epoxidation of cis-cyclooctene at 55 degrees C with tert-butylhydroperoxide (tBuOOH, 5.5 M in decane or 70% aqueous) as the oxidant. Biphasic solid-liquid or triphasic solid-organic-aqueous mixtures are formed, and 1,2-epoxycyclooctane is the only reaction product. When n-hexane is employed as a cosolvent and tBuOOH(decane) is the oxidant, the catalytic reaction is heterogeneous in nature, and the solid catalyst can be recycled and reused without a loss of activity. For comparison, the catalytic performance of the precursor 1 was also investigated. The IR spectra of solids recovered after catalysis indicate that 1 transforms into the organic-inorganic polymer [MoO(3)(bipy)] when the oxidant is tBuOOH(decane) and compound 2 when the oxidant is 70% aqueous tBuOOH.
Abrantes
Marta
M
Centro de Química Estrutural, Complexo Interdisciplinar, Instituto Superior Técnico, Universidade Técnica de Lisboa, Av. Rovisco Pais, 1, 1049-001 Lisboa, Portugal. marta.abrantes@ist.utl.pt
Amarante
Tatiana R
TR
Antunes
Margarida M
MM
Gago
Sandra
S
Paz
Filipe A Almeida
FA
Margiolaki
Irene
I
Rodrigues
Alírio E
AE
Pillinger
Martyn
M
Valente
Anabela A
AA
Gonçalves
Isabel S
IS
D015082:2,2'-Dipyridyl / Q000737:chemistry*; D002384:Catalysis; D018360:Crystallography, X-Ray; D034242:Cyclooctanes / Q000737:chemistry*; D004852:Epoxy Compounds / Q000737:chemistry*; D006358:Hot Temperature; D008872:Microwaves; D008958:Models, Molecular; D008968:Molecular Conformation; D008982:Molybdenum / Q000737:chemistry*; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D013237:Stereoisomerism
D034242:Cyclooctanes; D004852:Epoxy Compounds; D009942:Organometallic Compounds; D015082:2,2'-Dipyridyl; D008982:Molybdenum