| Abstract |
The new mono- and dicopper(II) complexes [Cu(H(3)L(1))(NCS)] (1) and [Cu(2)(mu-HL(2))(2)(NCS)(2)] (2) were easily self-assembled from Cu(CH(3)COO)(2)center dot H(2)O, NaNCS, NaOH and N,N,N ,N -tetrakis(2-hydroxyethyl)ethylenediamine (H(4)L(1)) or N-ethyldiethanolamine (H(2)L(2)), respectively. They were fully characterized by IR spectroscopy, ESI-MS(+/-), elemental and single-crystal X-ray diffraction analyses, and applied as homogeneous catalysts for (i) the oxidation of alkanes by r-BuOOH in air to alkyl peroxides, alcohols and ketones, and in turn the oxidation of alcohols to ketones, and (ii) the single-pot aqueous medium hydrocarboxylation, by CO, H(2)O and K(2)S(2)O(8), of various linear and cyclic C(n) (n = 5-8) alkanes into the corresponding C(n+1) carboxylic acids. Compound 1 was significantly more active in the oxygenation of alkanes and oxidation of alcohols, allowing to achieve 18\% yield (TON = 800) of oxygenates in the oxidation of cyclohexane, and 78\% yield (TON = 780) of cyclohexanone in the oxidation of cyclohexanol. In alkane hydrocarboxylations, 1 and 2 exhibited comparable activities with the total yields (based on alkane) of carboxylic acids attaining 39\%. The selectivity parameters for oxidative transformations were measured and discussed, supporting free-radical mechanisms. (C) 2011 Elsevier B.V. All rights reserved. |
