Iron Alkoxide Research Articles

Preparation of hierarchically nanofibrous membrane and its high adaptability in hexavalent chromium removal from water

Removal of hexavalent chromium Cr (VI) from water is a key problem in environmental remediation due to its high toxicity. In this work, a special sol of iron alkoxide was first prepared and added into a polymer (thermal plastic elastomer ester (TPEE)) solution to form the electrospinning precursor, then for the first time, hierarchically nanofibrous membrane was fabricated by electrospinning technique combined with hydrothermal strategy. The synthesized membrane exhibited high efficiency for the removal of Cr (VI) from water. X-ray diffraction (XRD) and scanning electron microscopy (SEM) revealed that the resulting nanofibrous membrane posses high crystallinity as well as hierarchical structure. The controlled experiments results and X-ray photoelectron spectroscopy (XPS) characterization indicated that the Cr (VI) removal ability of the membrane was mainly attributed to the adsorption and reduction of Cr (VI)–Cr (III), which is much less toxic, because of the hierarchical structure and the exposed iron oxide active sites. The research of adsorption isotherm suggested that the adsorption of Cr onto the membrane was Freundlich adsorption, which further displayed that the main Cr (VI) removal was attributed to the reduction of Cr (VI)–Cr (III). Therefore, this study provides a promising hierarchically nanostructured membrane with desirable Cr (VI) removal ability and easy solid–liquid separation property.

Synthesis of Hierarchical Hollow-Structured Single-Crystalline Magnetite (Fe3O4) Microspheres: The Highly Powerful Storage versus Lithium as an Anode for Lithium Ion Batteries

Hierarchical hollow Fe3O4 (H–Fe3O4) microspheres are prepared by the controlled thermal decomposition of an iron alkoxide precursor, which is obtained via an ethylene glycol (EG) mediated solvothermal reaction of ferric chloride hexahydrate (FeCl3·6H2O), sodium acetate (NaAc), and polyvinylpyrrolidone (PVP). The microspheres are characterized by the assembly of highly oriented primary nanoparticles and have a single-crystal feature. As the anode materials for the lithium-ion batteries, the resultant H–Fe3O4 microspheres show high specific capacity and good cycle stability (851.9 mAh g–1 at 1 C and 750.1 mAh g–1 at 3 C up to 50 cycles), as well as enhanced rate capability. The excellent electrochemical performance can be attributed to the high interfacial contact area between the microspheres and electrolyte, and good accommodation of volume change arising from the synergetic effect of the hierarchical hollow structure. It is suggested that the H–Fe3O4 microsphere synthesized by this method is a promising anode material for high energy-density lithium-ion batteries.

3-D self-assembly of flower-like particles via microwave irradiation for water treatment

Three-dimensional (3-D) flower-like shape (FLS) Fe3O4 and Fe particles were successfully synthesized using FLS precursor particles that are prepared through a facile microwave-assisted reaction. The mechanism underlying the self-assembly process and shape evolution of FLS particles was systematically investigated by changing reaction parameters such as reaction temperature, reaction time and reaction pressure. During the reaction, iron alkoxide, α-Fe2O3 and FeOOH nanoparticles are formed first and are subsequently transformed to 3-D hierarchical FLS particles by the self-assembly of the primary nanoparticles. Reaction temperature and pressure play critical roles in the formation of the hierarchical flower-like superstructure. There is an optimum window of the reaction temperature (∼180 °C) for the formation of 3-D FLS particles, which is attributed to the competition between the self-assembly process and growth process of the nanoparticles. Also, since FeCl3, ethylene glycol, and urea are used together as raw materials, the appearance of FLS particles is strongly dependent on the reaction pressure. As the reaction pressure becomes larger than 1 MPa, the flake type particles become more thermodynamically favorable than the FLS particles, due to the limited decomposition of urea. Brunauer–Emmett–Teller (BET) analysis shows that FLS particles have a large surface area (>40 m2 g−1). Because of their high specific surface area and intrinsic reactivity, FLS particles efficiently remove sulfur ions in aqueous solution. This suggests that these flower-like particles can be promising materials to treat toxic gas such as H2S in an environment-friendly way.

Polymerization of Lactide Catalyzed by Diketiminato Iron (II) Alkoxide Complex

Lactide polymerization were carried out by using diketiminato iron (II) alkoxide complexes HC(C(CH3)N-2,6-iPr2C6H3)2FeOiPr as catalyst. The iron (II) alkoxide complex bearing bulky isopropyl ortho substituents showed moderate activity for the rac-lactide polymerization, and gave the polylactide (PLA) with high molecular weight. In the microstructures of polymers generated with the iron (II) catalyst, no stereoslective polymerization of rac-lactide has been detected. Results have shown that the conversion of lactide depend on the iron complex/monomer feed ratio and the reaction temperature.

Morphology-Controlled Synthesis and Electromagnetic Properties of Porous Fe3O4 Nanostructures from Iron Alkoxide Precursors

Well-defined porous Fe3O4 flower-like nanostructures have been synthesized by decomposition of the iron alkoxide precursors that are prepared by heating up the solution of FeCl3·6H2O, urea, and surfactant in ethylene glycol. Time-dependent SEM studies indicate that the structure evolution of iron alkoxide precursors contains a fast nucleation of primary nanoparticles followed by a subsequent growth. By varying the amount of surfactant in the solution, the morphology and microstructure of the iron alkoxide precursors can be controlled. After calcination, the flower-like nanostructures of the precursors are maintained in the final products Fe3O4, with each petal of the flower being transformed from a dense structure with a smooth surface into a highly porous structure consisting of interconnected nanoparticles due to the removal of organic species in the iron alkoxide by pyrolysis. Compared to traditional ferrites and ferromagnetic alloys, the complex permittivity of the flower-like porous Fe3O4 samples is ...

Synthesis, Characterization, and Electrochemical Properties of a Series of Sterically Varied Iron(II) Alkoxide Precursors and Their Resultant Nanoparticles

A new family of iron(II) aryloxide [Fe(OAr)(2)(py)(x)] precursors was synthesized from the alcoholysis of iron(II) mesityl [Fe(Mes)(2)] in pyridine (py) using a series of sterically varied 2-alkyl phenols (alkyl = methyl (H-oMP), isopropyl (H-oPP), tert-butyl (H-oBP)) and 2,6-dialkyl phenols (alkyl = methyl (H-DMP), isopropyl (H-DIP), tert-butyl (H-DBP), phenyl (H-DPhP)). All of the products were found to be mononuclear and structurally characterized as [Fe(OAr)(2)(py)(x)] (x = 3 OAr = oMP (1), oPP (2), oBP (3), DMP (4), DIP (5); x = 2 OAr = DBP (6), DPhP (7)). The use of tris-tert-butoxysilanol (OSi(OBu(t))(3) = TOBS) led to isolation of [Fe(TOBS)(2)(py)(2)] (8). The new Fe(OAr)(2)(py)(x) (1-6) were found, under solvothermal conditions, to produce nanodots identified by PXRD as the γ-maghemite phase. The model precursor 3 and the nanoparticles 6n were evaluated using electrochemical methods. Cyclic voltammetry for 3 revealed multiple irreversible oxidation peaks, which have been tentatively attributed to the loss of alkoxide ligand coupled with the deposition of a solid Fe-containing coating on the electrode. This coating was stable out to the voltage limits for the acetonitrile solvent.

Facile synthesis of hierarchically structured Fe 3O 4/carbon micro-flowers and their application to lithium-ion battery anodes

A flower-like Fe 3O 4/carbon nanocomposite with nano/micro hierarchical structure is prepared by controlled thermal decomposition of the iron alkoxide precursor, which is obtained via an ethylene glycol-mediated solvothermal reaction of FeCl 3 and hexamethylenetetramine (HMT) in the absence of any surfactant. The nanocomposite is characterized by the assembly of porous nanoflakes consisting of Fe 3O 4 nanoparticles and amorphous carbon that is in situ generated from the organic components of alkoxide precursor. When used as the anode materials for the lithium-ion batteries, the resultant nanocomposite shows high capacity and good cycle stability (1030 m Ah g −1 at a current density of 0.2 C up to 150 cycles), as well as enhanced rate capability. The excellent electrochemical performance can be attributed to the high structural stability and high rate of ionic/electronic conduction arising from the synergetic effect of the unique nano/micro hierarchical structure and conductive carbon coating.

Synthesis of ultrasmall magnetic iron oxide nanoparticles and study of their colloid and surface chemistry

Colloidal nanoparticles of Fe 3O 4 (4 nm) were synthesized by high-temperature hydrolysis of chelated iron (II) and (III) diethylene glycol alkoxide complexes in a solution of the parent alcohol (H 2DEG) without using capping ligands or surfactants: [Fe(DEG)Cl 2] 2−+2[Fe(DEG)Cl 3] 2−+2H 2O+2OH −→Fe 3O 4+3H 2DEG+8Cl − The obtained particles were reacted with different small-molecule polydentate ligands, and the resulting adducts were tested for aqueous colloid formation. Both the carboxyl and α-hydroxyl groups of the hydroxyacids are involved in coordination to the nanoparticles’ surface. This coordination provides the major contribution to the stability of the ligand-coated nanoparticles against hydrolysis.

Carbon−Oxygen Bond Cleavage by Bis(imino)pyridine Iron Compounds: Catalyst Deactivation Pathways and Observation of Acyl C−O Bond Cleavage in Esters

Investigations into the substrate scope of bis(imino)pyridine iron-catalyzed hydrogenation and [2π + 2π] diene cyclization reactions identified C−O bond cleavage as a principal deactivation pathway. Addition of diallyl or allyl ethyl ether to the bis(imino)pyridine iron dinitrogen complex, (iPrPDI)Fe(N2)2 (iPrPDI = 2,6-(2,6-iPr2-C6H3N═CMe)2C5H3N, 1-(N2)2), under a dinitrogen atmosphere resulted in facile cleavage of the C−O bond and yielded a mixture of the corresponding paramagnetic iron allyl and alkoxide complexes. For ethyl vinyl ether, clean and selective formation of the iron ethoxide was observed with concomitant loss of the vinyl fragment. In situ monitoring of the catalytic hydrogenation of trans-methyl cinnamate established ester C−O bond cleavage as a competing process. Stoichiometric reactions between 1-(N2)2 and allyl and vinyl acetate also produced facile C−O oxidative addition. For the latter, a six coordinate diamagnetic bis(imino)pyridine acetatoxy iron vinyl compound was obtained and cha...

Synthesis of monodisperse nanocrystals of high crystallinity magnetite through solvothermal process

A solvothermal process has been applied for the preparation of monodisperse magnetite by the decomposition of chelate iron alkoxide complexes with diethylene glycol. The magnetite nanocrystals have narrow size distribution and high crystallinity. The Fe3O4 products are characterized by X-ray diffraction and transmission electron microscopy, Mössbauer spectra and vibrating sample magnetometer (VSM). The nanoscale (∼50nm) Fe3O4 powder obtained at 230°C for 6h possessed a saturation magnetization of 86.6emug−1, a little lower than that of the correspondent bulk Fe3O4 (92emug−1). It is suggested that the high-crystallized Fe3O4 nanocrystals formed under appropriate solvothermal conditions should be responsible for the increased saturation magnetization in the nanosized Fe3O4.

Synthesis of Variable-Sized Nanocrystals of Fe3O4 with High Surface Reactivity

A new rational method of synthesis of nanocrystalline iron (II, III) oxide is based on the elevated-temperature hydrolysis of chelate iron alkoxide complexes in solutions of corresponding alcohol, diethylene glycol, and N-methyl diethanolamine. The rates of reaction and crystallization are easily tuned by varying the concentration of reactants and changing the temperature. The size of the nanocrystals is controlled by changing the complexing strength of the reaction medium: 5.7 nm in diethylene glycol, 16.8 nm in N-methyl diethanolamine, and 12.7 nm in a 1:1 mixture of both solvents. The nanocrystalline powdered Fe3O4 products were isolated with a high yield. The surface of the obtained nanocrystals is passivated by molecules of adsorbed donating solvent that provide stability against agglomeration, provide solubility in polar protic solvents (water and methanol), and allow reactions at the nanocrystal surface.

Reactivity of a (μ-Oxo)(μ-hydroxo)diiron(III) Diamond Core with Water, Urea, Substituted Ureas, and Acetamide

A series of iron(III) complexes of the tetradentate ligand BPMEN (N,N'-dimethyl-N,N'-bis(2-pyridylmethyl)ethane-1,2-diamine) were prepared and structurally characterized. Complex [Fe(2)(mu-O)(mu-OH)(BPMEN)(2)](ClO(4))(3) (1) contains a (mu-oxo)(mu-hydroxo)diiron(III) diamond core. Complex [Fe(BPMEN)(urea)(OEt)](ClO(4))(2) (2) is a rare example of a mononuclear non-heme iron(III) alkoxide complex. Complexes [Fe(2)(mu-O)(mu-OC(NH(2))NH)(BPMEN)(2)](ClO(4))(3) (3) and [Fe(2)(mu-O)(mu-OC(NHMe)NH)(BPMEN)(2)](ClO(4))(3) (4) feature N,O-bridging deprotonated urea ligands. The kinetics and equilibrium of the reactions of 1 with ligands L (L = water, urea, 1-methylurea, 1,1-dimethylurea, 1,3-dimethylurea, 1,1,3,3-tetramethylurea, and acetamide) in acetonitrile solutions were studied by stopped-flow UV-vis spectrophotometry, NMR, and mass spectrometry. All these ligands react with 1 in a rapid equilibrium, opening the four-membered Fe(III)(mu-O)(mu-OH)Fe(III) core and forming intermediates with a (HO)Fe(III)(mu-O)Fe(III)(L) core. The entropy and enthalpy for urea binding through oxygen are DeltaH degrees = -25 kJ mol(-1) and DeltaS degrees = -53.4 J mol(-1) K(-1) with an equilibrium constant of K(1) = 37 L mol(-1) at 25 degrees C. Addition of methyl groups on one of the urea nitrogen did not affect this reaction, but the addition of methyl groups on both nitrogens considerably decreased the value of K(1). An opening of the hydroxo bridge in the diamond core complex [Fe(2)(mu-O)(mu-OH)(BPMEN)(2)] is a rapid associative process, with activation enthalpy of about 60 kJ mol(-1) and activation entropies ranging from -25 to -43 J mol(-1) K(-1). For the incoming ligands with the -CONH(2) functionality (urea, 1-methylurea, 1,1-dimethylurea, and acetamide), a second, slow step occurs, leading to the formation of stable N,O-coordinated amidate diiron(III) species such as 3 and 4. The rate of this ring-closure reaction is controlled by the steric bulk of the incoming ligand and by the acidity of the amide group.

Preparation of monodisperse magnetic particles by hydrolysis of iron alkoxide

The synthesis of iron oxide particles was carried out by the hydrolysis of iron tri-n-butoxide in an octanol/acetonitrile solution. The morphology of the particles formed was found to depend on composition of the mixture of solvents used and also on the method of its addition, i.e. either instantaneous or continuous. The data of apparent reaction rate revealed that the selection of reaction conditions controlling the reaction rate was the most important factor for achieving formation of monodispersed particles. These particles were subsequently used for preparation of magnetic particles by de-oxidation process.With respect to the relationships between the reduction condition and magnetic characteristics of the particles formed in this process, it was found that the particles synthesized showed a saturation magnetization magnetic susceptibility greater than that of commercial magnetite when they were reduced at a temperature higher than 573 K under a hydrogen atmosphere. The particles obtained after reduction treatment at 523 K for 3 h were identified as γ-Fe2O3 and those at temperature higher than 623 K for 3 h as α-Fe types, respectively, by using powder X-ray diffraction technique.A suspension obtained using the monodisperse magnetic particles in silicone oil was prepared and its rheological characteristic was determined using a parallel-plate rheometer and was found to have an apparent magnetorheological (MR) effect. It is believed that the monodisperse magnetic particles obtained in this work can be used as a component of a model MR fluid to elucidate the general mechanism of cluster formation of particles in such fluids.

Tuning low-coordinate metal environments: high spin d5–d7 complexes supported by bis(phosphinimino)methyl ligation

Treatment of FeCl2 with the lithium derivative of [CH2(Ph2PNC6H2Me3-2,4,6)2] in THF and crystallisation from Et2O gave the ‘ate’ complex [{CH(Ph2PNC6H2Me3-2,4,6)2}Fe(μ-Cl)2Li(THF)(OEt2)] in which the iron is four-coordinate and the chlorides bridge to lithium. Treatment of [M{N(SiMe3)}2] (M = Mn, Fe, Co) with [CH2(Ph2PNC6H2Me3-2,4,6)2] in toluene afforded the complexes [{CH(Ph2PNC6H2Me3-2,4,6)2}MN(SiMe3)2] which all feature essentially planar N(1)–N(2)–N(3)–M coordination. The carbanionic character of the bis(phosphinimino)methyl ligand results in close C(1)–M contacts in both the Mn and Co complexes effectively raising the coordination number to four. The analogous iron compound is strictly three-coordinate as demonstrated by X-ray crystallography and 57Fe Mossbauer. However protonolysis of this compound with Ph3COH yields the iron alkoxide [{CH(Ph2PNC6H2Me3-2,4,6)2}FeOCPh3] that features a close C(1)–Fe contact of 2.375 A. Although the iron centre in this complex is only marginally pyramidalised by this contact, its 57Fe Mossbauer spectrum indicates a significant perturbation to the local electronic environment at the metal.

A well-defined iron(ii) alkoxide initiator for the controlled polymerisation of lactide

The three-coordinate iron(II) complex, (But-BDI)FeOBut [But-BDI = HC(C(But)N-2,6-iPr2C6H3)2] is found to be a highly active initiator for the polymerisation of lactide and caprolactone at room temperature.

Molecular Structure of Interphases Formed by Plasma Polymerized Acetylene Films and Steel Substrates

ABSTRACTThe goal of this research was to determine the molecular structure of interfaces between plasma polymerized acetylene films and steel substrates and to elucidate the mechanisms by which the films adhere to the substrates. Inductively-coupled, RF-powered plasma reactors interfaced to an FTIR spectrometer and to an XPS spectrometer were used to deposit films ranging in thickness from a few tens of nanometers to approximately one nanometer onto polished steel substrates. As the thickness of the films was decreased, features in the XPS and FTIR spectra that were characteristic of the bulk of the films decreased in intensity and features characteristic of the interface increased in intensity. A band was observed near 1706 cm−1 in FTIR spectra of the thickest films and attributed to carbonyl groups. Bands were observed near 1600 and 1045 cm−1 in spectra of the thinnest films and attributed to iron carboxylate and iron alkoxide groups that were responsible for adhesion of the films to the substrates. Oxygen required to form these groups was available from water or oxygen molecules adsorbed onto the walls of the reactor.

Fe9O3(OC2H5)21·C2H5OH − A New Structure Type of an Uncharged Iron(III) Oxide−Alkoxide Cluster

A new nona iron(III) oxide-alkoxide cluster has been prepared by the treatment of FeCl3 with three equivalents of sodium ethoxide. The molecule is the first example of a neutral iron(III) alkoxide cluster based on OEt ligands and shows a paramagnetic moment of 13.4(1) μB at 293 K in the solid state.

A simple, efficient route to a .mu.6-oxo-centered hexanuclear iron(III) alkoxide complex: preparation and structure of Na2Fe6O(OCH3)18.cntdot.6CH3OH

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTA simple, efficient route to a .mu.6-oxo-centered hexanuclear iron(III) alkoxide complex: preparation and structure of Na2Fe6O(OCH3)18.cntdot.6CH3OHKaspar Hegetschweiler, Helmut W. Schmalle, Hans M. Streit, Volker Gramlich, Hans Ulrich Hund, and Isidor ErniCite this: Inorg. Chem. 1992, 31, 7, 1299–1302Publication Date (Print):April 1, 1992Publication History Published online1 May 2002Published inissue 1 April 1992https://doi.org/10.1021/ic00033a032RIGHTS & PERMISSIONSArticle Views251Altmetric-Citations70LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (525 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

High temperature synthesis and characteristics of Al-substituted iron alkoxide

A crystalline solid identified as Al-substituted iron alkoxide is obtained from the reaction at 246° C of glycerol with synthetic Al-bearing goethite, when the latter's composition is: Fe 0.904Al 0.096 OOH. X-ray powder diffractograms (XRD) of this solid show a significant shift of the d spacings in comparison to a previously reported pure iron glycerate complex derived from synthetic α-FeOOH. The composition of the metallic alkoxide, calculated from chemical analysis data is: [(C 3H 5O 3Fe 0.98Al 0.02)] n . When this powder is calcined at 1000°C, well-crystallized Al-substituted hematite is produced, whose XRD patterns indicate a shift of the characteristic hematite lines to lower values. The partial (isomorphic) substitution of Fe by Al may also be ascertained from the hydrolysis of the [(C 3H 5O 3Fe 0.98Al 0.02)] n complex by boiling water; then the XRD and chemical analyses of the resulting product show limited formation of a spinel solid solution. In contrast, hydrolysis of pure iron alkoxide yields high amounts of ferrimagnetic spinel (mainly FeO·Fe 2O 3). Some characteristics of the Al-substituted iron alkoxide and of its hydrolysis and calcination products are briefly examined.

Topotactic conversions of γ-FeOOH and comparative transformation methods of iron oxides in magnetic spinels

The DTA of a natural, well crystallized lepidocrocite sample containing small amounts of goethite, quartz and manganese shows that the conversion of γ-FeOOH to α-Fe 2O 3 (through the γ-Fe 2O 3 metastable phase) occurs at 440°C, whereas in pure, synthetic γ-FeOOH the exothermic peak appears at ~ 500°. Quartz (1.4% SiO 2) is not affected, nor does it hamper the transformation of FeOOH into magnetic spinels, when the sample is reacted with glycerol at reflux temperature followed by hydrolysis of the resulting solid (iron alkoxide) by boiling H 2O. Starting γ-FeOOH and final solid products are characterized by XRD and IR spectroscopy. This reaction is also discussed comparatively with the solid state transformations of iron oxides into magnetic materials by a combination of heating and grinding-pressing cycles of disks containing alkali halides as diluting agents.