1834-30-6Relevant articles and documents
Synthesis and reactivity of haloacetato derivatives of iron(II) including the crystal and the molecular structure of [Fe(CF3COOH) 2(μ-CF3COO)2]n
Marchetti, Fabio,Melai, Bernardo,Pampaloni, Guido,Zacchini, Stefano
, p. 3378 - 3384 (2007)
The syntheses of haloacetates of iron(II) and their reactivity are described. The compound Fe(CF3COO)2, 1, crystallizes from CF3COOH/(CF3CO)2O solution as the polynuclear [Fe(CF3COO)2(CF3COOH)2] n, 2, which contains bridging trifluoroacetates and monodentate trifluoroacetic acid groups. Fe(CF3COO)2(DMF)x, as obtained from Fe(CO)5 and CF3COOH/(CF 3CO)2O in DMF, reacts with dioxygen at room temperature to give two μ3-oxo compounds, namely, [Fe3(μ 3-O)(CF3COO)6(DMF)3], 3, a Fe (II)-Fe(III)-Fe(III) derivative, and [Fe 4(μ3-O)2(μ2-CF 3COO)6(CF3COO)2(DMF)4], 4, containing Fe(III) atoms only, which have been characterized by X-ray diffraction methods. Iron(II) chloro- and bromoacetates can be isolated by exchange reactions of iron(II) acetate with chloro- and bromo-substituted acetic acids in moderate to good yields. The stability of iron(II) haloacetates decreases on increasing the atomic weight and the number of halogens on the α-carbon atom. The species Fe(CX3COO)2 (X = Cl, 7; Br, 8), in THF solution, slowly convert into [Fe3(μ3-O) (CCl3COO)6(THF)3], 11, or [Fe 3(μ3-O)(CBr3COO)6(THF) 3][FeBr4], 10, respectively. Likewise, when iron(II) acetate (or trifluoroacetate) is left for several hours in the presence of a variety of haloacetic acids in THF, selective formation of different species, depending on the nature of the starting compound and of the acid employed, is observed. The formation of these products is the result of C-X bond activation (X = Cl, Br) and haloacetato decomposition, which occurs with concomitant oxidation at the metal centers. Carboxylic acid degradation species (CH 2XCOOH, CX4, CX3H, CX2H2, X = Cl, Br) have been observed by GC-MS.
Electric properties of Co substituted Ni-Zn ferrites
Ghodake,Kambale,Salvi,Sawant,Suryavanshi
, p. 830 - 834 (2009)
Nanocrystalline Ni-Co-Zn ferrites have been synthesized by chemical co precipitation method, using oxalate precursors. The phase formation of the sintered ferrite was confirmed by X-ray diffraction study. The lattice parameter 'a' increases with the addit
Studies on initial permeability and loss factor in Ni-Zn ferrites synthesized by oxalate precursors
Chaudhari,Kambale,Patil,Sawant,Suryavanshi
, p. 1713 - 1719 (2010)
NiXZn1-XFe2O4 ferrites with (X = 0.28-0.40 in step of 0.2) have been synthesized by oxalate precursor method and investigated for their, initial permeability and loss factor measurements. Initial permeability has been observed to increase with the increase in Ni 2+ up to X = 0.32, beyond which it decreases. The variation of initial permeability has been explained by considering the factors such as grain size, saturation magnetization and anisotropy constant. Thermal variation of initial permeability reveals a peak height in μi-T curves which tends to increase with increase in Ni2+ content. μi-T curves also exhibit thermal hysteresis, which reveals the inverse relationship between the difference in heating and cooling curves at which hysteresis falls between Hopkinson peak and Tc with value of initial permeability. Loss factor values are small which is attributed to high density of the samples and processing techniques.
Burger, K.,Zay, I.,Nagy, G. Takacsi
, p. 231 - 236 (1983)
Synthesis, characterization and thermal analysis of [Fe(N2H4)2(CH3COO)2]
Jiji, E. R.,Aravindakshan, K. K.
, p. 65 - 72 (1995)
[Fe(N2H4)2(CH3COO)2] was synthesized and characterized for the first time by chemical analysis, magnetic measurements, electronic and IR spectral studies. Its thermal reactivity was ascertained by the
Magnetic properties of NiCuZn ferrites synthesized by oxalate precursor method
Ghodake,Ghodake,Sawant,Suryavanshi,Bakare
, p. 110 - 119 (2006)
Ni-Cu-Zn ferrites have been synthesized by employing co-precipitation technique using oxalate precursors. X-ray diffractograms did not show impurity phases, indicating single-phase formation of the ferrites. The diffractograms of oxalate complex decomposed at 650 °C show that ferritization is complete up to 650 °C. Lattice parameter a (A?) was found to decrease with the addition of Ni2+ which is attributed to ionic sizes of Ni2+ (0.69 A?), which replaces Cu2+ (0.72 A?). From the thermogravimetric studies it is observed that the experimentally observed total mass loss (%), agrees with theoretically calculated mass loss (%) indicating maintenance of requisite stoichiometry. Initial permeability (μi ) shows increase when Ni2+ is added up to x = 0.15 while for (x > 0.15), it decreases. The increase in initial permeability (μi) is attributed to monotonic increase in Ms, and K1 on addition of Ni2+. However, the microstructure and density (porosity) also influence μi variations. The decrease in μi is attributable to increase of K1. The composition with density 91.14% exhibits large μi which also tends to increase with temperature up to 60 °C. Thus its usable range extends up to 60 °C. This samples has Tc near to 160 °C.
Thermal study of ferritization temperature of Cu-Mg-Zn ferrites: TG/DTG/DTA (STA) studies
Bhosale,Patil,Rane,Mahajan,Bakare,Sawant
, p. 159 - 165 (1998)
Oxalates of Cu2+, Mg2+, Zn2+ and Fe2+ were coprecipitated from the mixture of respective acetate solutions using 0.6 M oxalic acid solution to form a homogeneous solid solution MgxCu(0.5-x)Zn0.5Fe2 (C2O4)3·nH2O with x=0.00, 0.20, 0.25 and 0.40. To determine ferritization (formation of ferrite) temperature of resulting ferrite system, MgxCu(0.5-x)Zn0.5Fe2O4 with x=0.00, 0.20, 0.25 and 0.40, TG/DTG/DTA studies (STA) were carried out on coprecipitated oxalate complexes. These studies revealed the low ferritization temperature (326°-370°C) of the ferrite system and occurrence of simultaneous decomposition and ferritization processes. The ferrite system was characterized using X-ray diffraction study, which revealed the presence of single spinel phase.
Green-to-Red Electrochromic Fe(II) Metallo-Supramolecular Polyelectrolytes Self-Assembled from Fluorescent 2,6-Bis(2-pyridyl)pyrimidine Bithiophene
Pai, Sandesh,Moos, Michael,Schreck, Maximilian H.,Lambert, Christoph,Kurth, Dirk G.
, p. 1418 - 1432 (2017/02/15)
The structure and properties of metallo-supramolecular polyelectrolytes (MEPEs) self-assembled from rigid 2,6-bis(2-pyridyl)pyrimidine and the metal ions FeII and CoII are presented. While FeL1-MEPE (L1 = 1,4-bis[2,6-bis(2-pyridyl)pyrimidin-4-yl]benzene) is deep blue, FeL2- and CoL2-MEPE (L2 = 5,5′-bis[2,6-bis(2-pyridyl)pyrimidin-4-yl]-2,2′-bithiophene) are intense green and red in color, respectively. These novel MEPEs display a high extinction coefficient and solvatochromism. Ligand L2 shows a high absolute fluorescence quantum yield (Φf = 82%). Viscosity and static light-scattering measurements reveal that the molar masses of these MEPEs are in the range of 1 × 108 g/mol under the current experimental conditions. In water, FeL1-MEPE forms a viscous gel at 20 °C (c = 8 mM). Thin films of high optical quality are fabricated by dip coating on transparent conducting indium tin oxide (ITO) glass substrate. Optical, electrochemical, and electrochromic properties of the obtained MEPEs are presented. Green to red and blue to colorless electrochromism is observed for FeL2-MEPE and FeL1-MEPE, respectively. The results show that the electrochromic properties are affected by the ligand topology. The Fe-MEPEs show a reversible redox behavior of the FeII/FeIII couple at 0.86 and 0.82 V versus Fc+/Fc and display an excellent redox cycle stability under switching conditions. FeL2-MEPE in its oxidized state exhibits a broad absorption band covering the near-IR region (ca. 1500 nm) due to the ligand-to-metal charge transfer transition originating due to charge delocalization in the bithiophene spacer.
