- Syntheses, electronic structures, and EPR/UV-Vis-NIR spectroelectrochemistry of nickel(II), copper(II), and zinc(II) complexes with a tetradentate ligand based on S-methylisothiosemicarbazide
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Template condensation of 3,5-di-tert-butyl-2-hydroxybenzaldehyde S-methylisothiosemicarbazone with pentane-2,4-dione and triethyl orthoformate at elevated temperatures resulted in metal complexes of the type MIIL, where M = Ni and Cu and H2L = a novel tetradentate ligand. These complexes are relevant to the active site of the copper enzymes galactose oxidase and glyoxal oxidase. Demetalation of NiIIL with gaseous hydrogen chloride in chloroform afforded the metal-free ligand H2L. Then by the reaction of H2L with Zn(CH3COO) 2?2H2O in a 1:1 molar ratio in 1:2 chloroform/methanol, the complex ZnIIL(CH3OH) was prepared. The three metal complexes and the prepared ligand were characterized by spectroscopic methods (IR, UV-vis, and NMR spectroscopy), X-ray crystallography, and DFT calculations. Electrochemically generated one-electron oxidized metal complexes [NiL]+, [CuL]+, and [ZnL(CH 3OH)]+ and the metal-free ligand cation radical [H 2L]+? were studied by EPR/UV-vis-NIR and DFT calculations. These studies demonstrated the interaction between the metal ion and the phenoxyl radical.
- Arion, Vladimir B.,Rapta, Peter,Telser, Joshua,Shova, Sergiu S.,Breza, Martin,Luspai, Karol,Kozisek, Jozef
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- Nickel nanoparticles supported on MOF-5: Synthesis and catalytic hydrogenation properties
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Nickel nanoparticles (2-6 nm) were successfully deposited on MOF-5 (Zn 4O(BDC)3, BDC = 1,4-benzenedicarboxylate) by a facile wet impregnation strategy to prepare Ni@MOF-5 employing Ni(acac)2 (acac = acetylacetonate) as the precursor in absolute ethanol solvent owing to the sensitivity to the moisture of MOF-5. Ni@MOF-5 exhibited excellent catalytic activity for hydrogenation of C = C bond using crotonaldehyde as a probe molecule under mild reaction conditions (conversion > 90.0%, selectivity > 98.0%, 2.0 MPa, 100 °C, 40 min). In addition, the catalyst could be reused and the structure of MOF-5 framework was still maintained. Therefore, MOF-5 promised a novel candidate of support for hydrogenation catalyst.
- Zhao, Huahua,Song, Huanling,Chou, Lingjun
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p. 261 - 265
(2012/03/13)
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- Reaction of the framework 3d-organometallosiloxanes with acetylacetone
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A reaction of acetylacetone with the framework sandwich-type metallosiloxanes (MOS) of general formula [PhSiO2]6M 6[PhSiO2]6, where M = Cu, Ni, Mn, was studied by GPC, 1H and 29Si NMR spectroscopy, X-ray diffraction, elemental and functional analysis. The reaction involved replacement of the metal atoms with the hydrogen atoms and is accompanied by the formation of the corresponding chelate complexes M(acac)2. Displacement of the metal from the framework MOS leads to the destruction of molecular skeleton and formation of phenylsiloxanes containing Si-OH groups. The yield and composition of the reaction products considerably depend on the nature of the metal in [PhSiO2]6M6[ThSiO2]6. A selective substitution of the metal leads to the stereoregular hexahydroxyhexaphenylcyclohexasiloxane, [PhSiO(PH)]6, cis-isomer. The structure and composition of the crystalline hexahydroxyhexaphenylcyclohexasiloxane obtained were confirmed by 29Si NMR spectroscopy, X-ray diffraction study, and functional analysis, while its TMS derivative was studied with 1H NMR spectroscopy and GPC. Using a framework manganese phenylsiloxane as an example, a reversible character of the process has been established and an alternative synthesis of this compound from hexahydroxyhexaphenylcyclohexasiloxane and Mn(acac)2 has been accomplished for the first time.
- Sergienko,Cherkun,Myakushev,Korlyukov,Zavin
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p. 1369 - 1375
(2011/04/16)
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- Ni(acac)2/phosphine as an excellent precursor of nickel(0) for catalytic systems
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The coordination of phosphine ligands to nickel acetylacetonate was studied in toluene solution, and the first X-ray structure of the unstable complex trans-[Ni(acac)2(PMe2Ph)2] has been reported. A convenient procedure was developed to generate Ni(0) species in situ in solution from a Ni(acac)2 precursor, and their application in catalysis was demonstrated. A study of the reaction mechanism has suggested that water may play an important role in the formation of zerovalent nickel species. The nature of the Ni(0) species was confirmed by trapping with Ph 2S2, and the structure of the resulting complexes trans-[Ni(SPh)2L2] was established by X-ray analysis for L = PMe2Ph, PMePh2, PBu3.
- Ananikov, Valentine P.,Gayduk, Konstantin A.,Starikova, Zoya A.,Beletskaya, Irina P.
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p. 5098 - 5102
(2011/01/05)
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- Method and catalyst system for producing aromatic carbonates
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A method and catalyst system for economically producing aromatic carbonates from aromatic hydroxy compounds. In one embodiment, the present invention provides a method of carbonylating aromatic hydroxy compounds by contacting at least one aromatic hydroxy compound with oxygen and carbon monoxide in the presence of a carbonylation catalyst system that includes a catalytic amount of an inorganic co-catalyst containing zinc. In various alternative embodiments, the carbonylation catalyst system can include an effective amount of a palladium source and an effective amount of a halide composition. Further alternative embodiments can include catalytic amounts of various inorganic co-catalyst combinations.
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- Hydrogenation process
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Process for the hydrogenation of functionally substituted acetylenic compounds employing catalyst comprising nickel boride on an inorganic oxide support is disclosed. Functionally-substituted acetylenic compounds are selectively reduced under mild reaction conditions to give functionally-substituted cis-olefinic compounds in high yield.
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- Recent Advances in the Chemistry of Simple and Bimetallic Alkoxides of Later Transition Elements (with particular reference to the 3d' series)
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After giving a survey of the spurt in the literature during the last 4-5 years on the chemistry of later transition metals in general, a brief account has been presented of the recent work carried out in the author's laboratories on the simple and bimetallic alkoxides of later '3d' metals.The synthesis of a number of simple alkoxides of Cr(III and IV), Mn(II), Fe(II and III), Co(II), Ni(II) and Cu(II) has been described.Except for alkoxides of iron(III), Fe(OR)3 in general and Cr(OBut)4, almost all these alkoxides are non volatile and insoluble in organic solvents.These polymeric alkoxides of alter '3d' metals further differ from the alkoxides of earlier transition and main group metals in comparatively much lesser lability of their alkoxy groups.The sharp differences (again observed for the first time in metal alkoxide chemistry) in the alcoholysis reactivity of these alkoxides with changes in ramification of the alkyl group have been correlated with changes in their stereochemistry.Further, a large number of monomeric volatile bimetallic isopropoxides of the above metals with the general formula Mi)4>n, have been synthesised.Physico-chemical (spectroscopic and magnetic) properties of these derivatives indicate simple coordinated structures with tetraisopropoxyaluminate moieties functioning as bidentate and in some cases as tridentate ligands.
- Mehrotra, R. C.
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p. 715 - 722
(2007/10/02)
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- Novel alcohols
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Phenyl substituted unsaturated diols useful as complexing agents for nickel and starting materials for the production of polymers.
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