- Tungsten(V)-oxo and tungsten(VI)-dioxo complexes with oxygen, nitrogen, and sulfur ligands. Electrochemical, infrared, and electron paramagnetic resonance studies
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Six new tungsten(V)- and -(VI)-oxo complexes have been synthesized (WOCl3L, L = α,α′-bipyridyl and o-phenanthroline; WOClL2, WO2L2, L = 8-hydroxyquinoline and 8-mercaptoquinoline) and their electrochemical prope
- Rice,Kroneck,Spence
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- Synthesis and evaluation of bis-β-diketonate dioxotungsten(VI) complexes as precursors for the photodeposition of WO3 films
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In this paper non-stoichiometric tungsten oxide thin films have been successfully prepared by direct UV irradiation of bis-β-diketonate dioxotungsten(VI) precursor complexes spin-coated Si(1 0 0) substrates. Photodeposited films were characterized by Fourier transform-infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) and the surface morphology examined by Atomic Force Microscopy (AFM). The results of XRD analysis showed that the as-photodeposited WO 3-x films are amorphous and have a rougher surface than thermally treated films. Post-annealing of the films in air at 500 °C transforms the sub-oxides to a monoclinic WO3 phase.
- Buono-Core,Klahn,Castillo,Bustamante,Mu?oz,Cabello,Chornik
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- Biomimetic Oxidative Bromination by cis-Dioxidotungsten(VI) Complexes of Salan Type N,N’-Capped Linear Tetradentate Amino Bisphenol
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Reaction of [WVIO2(acac)2] (Hacac=acetylacetone) with salan-type dibasic tetradentate ONNO donor Mannich bases derived from ethylenediamine, formaldehyde and 2,4-di-tert-butylphenol (H2L1), 2-tert-butyl-4-methylphenol (H2L2), 2,4-dimethylphenol (H2L3) and 2,4-dichlorophenol (H2L4) in a 1 : 1 ([WVIO2(acac)2] : H2L) molar ratio in refluxing MeOH gave the corresponding cis-dioxidotungsten(VI) complexes [WVIO2L1] (1), [WVIO2L2] (2), [WVIO2L3] (3) and [WVIO2L4] (4), respectively. Characterization by elemental analysis, various spectroscopic (FT-IR, UV-vis, 1H and 13C NMR) studies, DFT calculations and single-crystal X-ray analysis of 2 and 3 suggest six-coordinated octahedral α-cis (symmetric) isomeric form of the complexes where ligands coordinate through the two phenolate oxygen and two amine nitrogen atoms (in a cis-α type symmetric binding mode) with one of the N atoms of the ligand and one of the terminal O atoms of the cis-WO2 group in the axial position. These complexes are potential catalyst precursors for the oxidative bromination of thymol and styrene. Thymol upon bromination gave three products, namely, 2-bromothymol, 4-bromothymol, and 2,4-dibromothymol; later one being the major product. Oxidative bromination of styrene resulted in 2-bromo-1-phenylethanol and 1-phenylethane-1,2-diol; the later one is the result of nucleophilic attack of water on the α as well as β carbons both of the initially formed 1,2-dibromo-1-phenylethane.
- Maurya, Mannar R.,Maurya, Shailendra K.,Kumar, Naveen,Gupta, Puneet
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p. 2724 - 2738
(2021/06/18)
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