| Abstract |
The aquasoluble [Cu(H2O)((CH3)(2)NCHO)(HL)] (2) and [Cu-2(CH3OH)(2)(mu-HL)(2)] (3) Cu-II complexes were prepared by reaction of Cu-II nitrate hydrate with the new 3-(2-hydroxy-4-carboxyphenylhydrazone)pentane-2,4-dione (H3L, 1), in the presence (for 2) or absence (for 3) of (n-C4H9)(2)SnO, and characterized by elemental analysis, IR spectroscopy and X-ray single crystal diffraction. Magnetic susceptibility measurements, in compound 3, reveal strong antiferromagnetic coupling between the Cu-II ions through the mu(2)-phenoxido-O atoms, J = -203(1) cm(-1). Complexes 2 and 3 act as catalyst precursors for the acid-free peroxidative oxidation of cyclohexane to the mixture of cyclohexyl hydroperoxide (primary product), cyclohexanol and cyclohexanone (TONs and yields up to 163 and 14.4\%, respectively), as well as for the selective aerobic oxidation of benzyl alcohols to benzaldehydes in aqueous solution, mediated by a TEMPO radical, under mild conditions (TONs and yields up to 390 and 94\%, respectively). In the alkane oxidations, 2 and 3 appear to behave as dual role catalysts combining, in one molecule, an active metal centre and an acidic promoting group, to provide a high activity of the system even without any acid promoter. |
