New Molybdenum(II) Complexes with alpha-Diimine Ligands: Synthesis, Structure, and Catalytic Activity in Olefin Epoxidation
authors Vasconcellos-Dias, M; Marreiros, J; Sales, R; Felix, V; Brandao, P; Nunes, CD; Calhorda, MJ
nationality International
author keywords molybdenum; allyl complexes; isomers; crystal structures; iminomethylpyridine; epoxidation
abstract Three new complexes [Mo(eta(3)-C3H5)Br(CO)(2){(PrN)-Pr-i=C(R)C5H4N}], where R = H (IMP = N-isopropyl 2-iminomethylpyridine), Me, and Ph, were synthesized and characterized, and were fluxional in solution. The most interesting feature was the presence, in the crystal structure of the IMP derivative, of the two main isomers (allyl and carbonyls exo), namely the equatorial isomer with the Br trans to the allyl and the equatorial with the Br trans to one carbonyl, the position trans to the allyl being occupied by the imine nitrogen atom. For the R = Me complex, the less common axial isomer was observed in the crystal. These complexes were immobilized in MCM-41 (MCM), following functionalization of the diimine ligands with Si(OEt)(3), in order to study the catalytic activity in olefin epoxidation of similar complexes as homogeneous and heterogeneous catalysts. FTIR, C-13- and Si-29-NMR, elemental analysis, and adsorption isotherms showed that the complexes were covalently bound to the MCM walls. The epoxidation activity was very good in both catalysts for the cis-cyclooctene and cis-hex-3-en-1-ol, but modest for the other substrates tested, and no relevant differences were found between the complexes and the Mo-containing materials as catalysts.
publisher MDPI
issn 1420-3049
year published 2019
volume 24
issue 3
digital object identifier (doi) 10.3390/molecules24030578
web of science category Biochemistry & Molecular Biology; Chemistry, Multidisciplinary
subject category Biochemistry & Molecular Biology; Chemistry
unique article identifier WOS:000458934000202
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