resumo
The multicomponent mixed-metal Cu-II/Mo-VI oxides/1,3-bis(1,2,4-triazol-4-yl)adamantane (tr(2)ad) system was thoroughly studied employing a compositional diagram approach. The concept allowed us to prepare three layered copper-molybdate hybrid solids [Cu-2(II)(tr(2)ad)(4)](Mo8O26) (1), [Cu-4(II)(mu(4)-O)(tr(2)ad)(2)(MoO4)(3)]center dot 7.5H(2)O (2), and [Cu-2(I)(tr(2)ad)(2)](Mo2O7). H2O (3), and to elucidate the relationship between initial reagent concentration/stoichiometry and the stability of the resultant structural motifs. Compounds 1 and 2 were found to dominate throughout a wide crystallization range of the concentration triangle, whereas compound 3 was formed by redox processes in the narrow crystallization area having a high excess of Cu(OAc)(2)center dot H2O. Independent experiments carried out with Cu(OAc)(2) and (NH4)(6)Mo7O24 in the absence of tr(2)ad, under the same conditions, revealed the formation of low-valent and bimetallic oxides, including Cu2O, MoO2, Cu(Mo3O10)center dot H2O, and Cu-3(MoO4)(2)(OH)(2). Compounds 1 and 2 show high thermal and chemical stability as examined as catalysts in the epoxidation of cis-cyclooctene and the oxidation of benzyl alcohol (BzOH) with different types of oxidants. The oxidation reaction of BzOH using tert-butyl hydroperoidde (TBHP) as the oxidant, in the presence of 1 or 2, led to benzaldehyde and benzoic acid (PhCO2H), with the latter being formed in up to 90% yield at 24 h. The results suggest that 1 and 2 may be favorable heterogeneous catalysts for the synthesis of PhCO2H. Whereas compound 1 only reveals a weak ferromagnetic coupling between neighboring Cu-II centers (J = 0.41 cm(-1)), compound 2 shows distinct intraduster antiferromagnetic exchange interactions (J = 29.9 cm(-1), J' = 25.7 cm(-1)), which consequently results in a diamagnetic ground state.
palavras-chave
TERT-BUTYL HYDROPEROXIDE; HYDROTHERMAL SYNTHESIS; COORDINATION POLYMERS; FUNCTIONALIZED ADAMANTANES; EFFICIENT OXIDATION; CRYSTAL-STRUCTURE; BUILDING-BLOCKS; COMPLEXES; SYSTEM; LIGANDS
categoria
Chemistry
autores
Senchyk, GA; Lysenko, AB; Babaryk, AA; Rusanov, EB; Krautscheid, H; Neves, P; Valente, AA; Goncalves, IS; Kramer, KW; Liu, SX; Decurtins, S; Domasevitch, KV
nossos autores
Anabela Tavares Aguiar Valente
Investigador Principal
Isabel Maria de Sousa Gonçalves
Professor associado
Patrícia dos Santos Neves
Investigador Auxiliaragradecimentos
Financial support by Deutsche Forschungsgemeinschaft, by the Ukrainian education program