| Abstract |
The reaction of copper(II) nitrate hydrate with sodium 2-[2-(2,4-dioxopentan-3-ylidene) hydrazinyl] terephthalate (Na2HL1) in the absence or presence of imidazole (im) leads to the new complexes [(H2O)Cu-0.(5)\(mu-L-1-1 kappa O:2 kappa N-3,O ,O ) Cu(H2O)(2)\](2) (1) and [Cu(im)(mu-HL1-1 kappa O:2 kappa N-3,O,O )] 2 (2), respectively, whereas the 1D coordination polymer [Cu-2(H2O)(2)(mu-H(2)L(2)1 kappa N-3,O,O :2 kappa O )(mu-L-2-1 kappa N-3,O,O :2 kappa N-2 ,O )](n) (3) is obtained from Cu(NO3)(2)center dot 2.5H(2)O and sodium 2-[2-(4,4-dimethyl-2,6-dioxocyclohexylidene) hydrazinyl]terephthalate (Na2HL2). All of the compounds were characterized by ESI-MS, IR spectroscopy, elemental analysis and X-ray diffraction analysis. Di-or tri-deprotonated ligands display different coordina-tion modes and lead to distinct nuclearities of the Cu-II complexes depending on the conditions used for the syntheses. Complexes 1-3 were successfully tested as dual-role catalysts for cyclohexane oxidation under acid-free conditions in the ionic liquid [1-butyl-3-methylimidazolium tetrafluoroborate, (bmim)(BF4)] as well as in acetonitrile. The application of the ionic liquid (IL) increased the product yield and turnover number and decreased the reaction time, in comparison with those for the use of the conventional acetonitrile solvent. Easy recycling of the catalyst, with preservation of almost the initial activity and selectivity, was also achieved by using the IL medium. |
