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Abstract(s)
The reactions of FeCl2 center dot 2H(2)O and 2,2,2-tris(1-pyrazolyl) ethanol HOCH2C(pz)(3) (1) (pz = pyrazolyl) afford [Fe{HOCH2C(pz)(3)}(2)][FeCl4]Cl (2), [Fe{HOCH2C(pz)(3)}(2)](2)[Fe2OCl6](Cl)(2)center dot 4H(2)O (3 center dot 4H(2)O), [Fe{HOCH2C(pz)(3)}(2)] [FeCl{HOCH2C(pz)(3)}(H2O)(2)](2)(Cl)(4) (4) or [Fe{HOCH2C(pz)(3)}(2)]Cl-2 (5), depending on the experimental conditions. Compounds 1-5 were isolated as air-stable crystalline solids and fully characterized, including (1-4) by single-crystal X-ray diffraction analyses. The latter technique revealed strong intermolecular H-bonds involving the OH group of the scorpionate 2 and 3 giving rise to 1D chains which, in 3, are further expanded to a 2D network with intercalated infinite and almost plane chains of H-interacting water molecules. In 4, intermolecular pi center dot center dot center dot pi interactions involving the pyrazolyl rings are relevant. Complexes 2-5 display a high solubility in water (S-25 degrees C ca. 10-12 mg mL(-1)), a favourable feature towards their application as catalysts (or catalyst precursors) for the peroxidative oxidation of cyclo-hexane to cyclohexanol and cyclohexanone, with aqueous H2O2/MeCN, at room temperature (TON values up to ca. 385). (C) 2011 Elsevier B. V. All rights reserved.
Description
Keywords
Cyclohexane Scorpionates Iron Catalysis Oxidation X-ray diffraction Copper triethanolamine complexes Organic molecular-crystals Hidrogen-peroxide Catalytic-activity Rhenium complexes Water clusters Hydrocarbon oxygenations Coordination chemistry Alkane hydroxylation ZN-II
Citation
SILVA, Telma F. S.; GUEDES DA SILVA, M. Fátima; MISHRA, Gopal S.; MARTINS, Luísa M. D. R. S.; POMBEIRO, Armando J. L. - Synthesis and structural characterization of iron complexes with 2,2,2-tris(1-pyrazolyl)ethanol ligands: application in the peroxidative oxidation of cyclohexane under mild conditions. Journal of Organometallic Chemistry. ISSN 0022-328X. Vol. 696, N.º 6 (2011) p.1310-1318