The Thermal Decomposition of Fe(NO3)3·9H2O

Using thermogravimetric analyses as well as isothermal gravimetric measurements, the thermal stability of the iron(III) nitrate nanohydrate has been determined. Several decomposition stages are the result of melting, evaporation and hydrolysis processes occurring in the salt—water system in the temperature range of 20–400°C. Some of the intermediates and the final product (-Fe₂O₃) are characterized by means of chemical analyses, X-ray diffraction patterns and IR spectra.This revised version was published online in November 2005 with corrections to the Cover Date.     

Kinetics of thermal dehydration and decomposition of Fe(III) chloride hydrate (FeCl3·xH 2O)

Fe(III) chloride hydrate (FeCl₃·xH₂O) undergoes simultaneous dehydration and dehydrochlorination from its molten phase in the temperature range 100–200C. The kinetics of these two parallel thermal processes has been studied by both isothermal and non-isothermal methods. Whereas for the dehydration reaction at temperature below 125C a second order rate model (F₂) fits well, a three-dimensional diffusion (D₃) model is found to fit better at temperature above 135C. For the dehydrochlorination reaction an interface growth controlled model of 1/3 order (F 1/3) appears to be the most suitable over a wide range of reaction. Dynamic thermogravimetry reveals two major steps in the temperature range 50–250C. The first step which corresponds to the loss of about 4 mols of H₂O, invariably follows second order kinetics (F₂). The second step which is predominantly a process of dehydrochlorination, generally fits mixed diffusion controlled models due to the overlapping with the dehydration process. There is an excellent agreement in results among the isothermal and non-isothermal methods of determining kinetic parameters.The authors are thankful to the Director, R. R. L. Bhubaneswar for his kind permission to publish this paper. One of the authors (SKM) is grateful to the Council of Scientific and Industrial Research, New Delhi, for the award of a Research Fellowship.     

On the thermal decomposition of [Fe2NiO(CH3COO)6(H2O)3]·2H2O

The heteronuclear-oxoacetate with the composition [Fe₂NiO(CH₂COO)₆(H₂O)₃]·2H₂O decomposed on heating, forming nickel ferrite NiFe₂O₄ and (depending on the decomposition conditions) in part other solid phases. H₂O, CH₃COOH, acetone and CO₂ were also formed in the decomposition. A reaction scheme is given for the decomposition. The products were porous powders with grain diameters between 3 and 10m. On increase of the temperature of decomposition from 300 to 800 C, the BET surface area and the surface area of the pores decreased, but only a small alteration in grain size was observed. As a result of thermal treatment in the temperature region abone 800C, larger aggregates of grains were formed in sintering processes.

---

Zusammenfassung Heteronukleare-Oxoazetate der Zusammensetzung [Fe₂NiO(CH₃COO)₆(H₂O)₃]·2H₂O werden durch Erhitzen zersetzt, wobei Nickelferrite NiFe₂O₄ und — in AbhÄngigkeit von den Bedingungen der Zersetzung — mit einem Teil anderer fester Phasen gebildet wird. In der Zersetzungsreaktion werden auch H₂O, CH₃COOH, Azeton und CO₂ gebildet. Es wird ein Reaktionsschema für die Zersetzung angegeben. Die Produkte sind poröse Pulver mit einem Korndurchmesser zwischen 3 und 10 m. Wird die Zersetzungstemperatur von 300 auf 800C erhöht, nimmt die BET-OberflÄche und die PorenoberflÄche ab, wobei sich die Korngrö\e aber nur wenig verÄndert. Im Ergebnis der WÄrmebehandlung im Temperaturbereich oberhalb 800C werden durch Sinterprozesse grö\ere Partikelaggregate gebildet.

     

(μ3-S)Fe2CoCu(PPh3)2(CO)8催化苯乙烯环丙烷化反应研究

以异核金属原子簇合物为催化剂的配位催化反应, 已在均相催化反应中得到应用. 簇合物中不同金属间的协同作用使其在催化领域展现出广阔的应用前景[1]. 然而,催化反应中簇合物是否以完整的骨架起催化作用,一直是人们关注的焦点. 在金属原子簇作催化剂前体的均相催化反应中,迄今只在少数的例子中有确凿的证据表明原子簇整体分子起催化作用[2]. 一般认为,在配位饱和的金属簇合物的催化反应中,簇合物稳定性越好,催化活性越差;而活性好的催化剂前体,簇合物骨架常解体.     

Electroconductance of single-crystal Li2 + x Fe 2 − 2x 2+ Fe x 3+ (MoO4)3 (x = 0.22)

Electrophysical properties of single-crystal Li_{2 + x} Fe _{2 ? 2x} ²⁺ Fe _x ³⁺ (MoO₄)₃ (x = 0.22) are studied at 25–400°C. It is found that the conduction is of electronic nature and the conductivity equals 5 × 10^-2 S/cm at 300°C. The activation energy for the electron transport is 0.23 eV. The conductance in molybdate Li_2.22Fe _1.56 ²⁺ Fe _0.22 ³⁺ (MoO₄)₃ is markedly anisotropic.     

Crystal Structure of [CH_3CH(OH)COO]_2Fe(H_2O)_2·H_2O

<正> The title compound C6H16O9Fe, Mr = 288. 13, was synthesized and crystallized in monoclinic space group P21/c, a = 9. 409(4), b = 5. 812(4), c= 22. 122(7)(?) , β=90. 80(3)°. V = 1209. 6(?)3, Z = 4, Dc=1. 572g/cm3, F(000) = 592, μ = 12. 73cm-1, R = 0. 063, Rw= 0. 068 for 1191 observed reflections. The iron atom is surrounded by O(1 - 6) in a distorted octahedron.     

Synthesis,Structure and Characterization of Three Metal Molybdate Hydrates: Fe(H2O)2(MoO4)2·H3O,NaCo2(MoO4)2(H3O2)and Mn2(MoO4)3·2H3O

Three metal molybdate hydrates,Fe(H2O)2(MoO4)2·H3O(FeMo),NaCo2(MoO4)2(H3O2)(CoMo)and Mn2(MoO4)3·2H3O(MnMo),were synthesized by the mixed-solvent-thermal methods and characterized by singlecrystal X-ray...     

XPS study of the electronic structure of heterometallic complexes [Fe2MO(O2CCH3)6(H2O)3] · 3H2O (M = Co,Ni)

Heterometallic compounds of general formula [Fe ₂ ^III M^IIO(O₂CR)₆(H₂O)₃] · 3H₂O (R = CH₃, M = Co, Ni; R = CCl₃, M = Co, Ni) have been studied by XPS. The compounds have been identified as high-spin complexes with metal atoms in oxidation states M(II) and M(III). Analysis of the XPS data revealed the tendency of the XPS pattern and magnetic parameters of molecules to change with a change in the electronic nature of metal atoms. The assignment is based on the degree of covalence of the M-O bond. In chloro-substituted heterocomplexes, electron density delocalization on the metal atoms with metal-to-ligand charge transfer through three bonds (M-O-C-C) is observed. The substitution in terminal groups leads to the change in the electron density distribution between the carboxylate and terminal groups.     

Physical properties of a new iron(III) complex, [3-pmH · 3-pm][Fe(NCS)4(3-pm)2]

The iron(III) compound of formula [3-pmH · 3-pm][Fe(NCS)₄(3-pm)₂] (3-pm = 3-(hydroxymethyl)pyridine) has been prepared by reaction between iron(III) thiocyanate and 3-(hydroxymethyl)pyridine in ethanol. The characterization was based on elemental analysis, infrared spectra and magnetic measurements. Single crystal X-ray diffraction methods show the monoclinic P2(1)/c space group with unit cell parameters: a = 12.295(3) Å, b = 15.854(3) Å, c = 16.880(3) Å, β = 100.12(3)° and Z = 4. The asymmetric unit of the title compound consists of [3-pmH · 3-pm]⁺ and [Fe(NCS)₄(3-pm)₂]^? held together by ionic interaction and a hydrogen bond interaction (O(68)–H(68) ··· O(78)). The central metal ion is octahedrally coordinated by six nitrogens, four from NCS^? form the equatorial plane and two from two 3-(hydroxymethyl)pyridines occupy axial positions. Magnetic susceptibility data in the temperature range 1.8–300 K show that iron(III) is high-spin S = 5/2(⁵ T _2g). Structural parameters and IR spectra of similar complexes are compared and discussed.     

The synthesis of the [Fe(Phen)3](iso-Bu2PS2)2 Complex. The crystal structures of [Fe(Phen)3](iso-Bu2PS2)2 · 5H2O and disulfan {iso-Bu2P(S)S}2

The complex [Fe(Phen)₃][iso-Bu₂PS₂)₂ (I) was synthesized and the single crystals of [Fe(Phen)₃](iso-Bu₂PS₂)₂ · 5H₂O (II) were grown. The disulfan {iso-Bu₂P(S)S}₂ (III) was isolated. Compound II consists of the complex cations [Fe(Phen)₃]²⁺, the outer-sphere anions iso-Bu₂PS ₂ ^? , and the molecules of water of crystallization. The coordination polyhedron of the Fe atom is a distorted N₆ octahedron. Complex I is diamagnetic, and thus, the full spin of the Fe²⁺ ion S = 0. The structure of III is built of the molecules containing the S-S bridge 2.061(1) Å in length.     

Computer simulation study of thermodynamic scaling of dynamics of 2Ca(NO3)2·3KNO3

Molecular dynamics (MD) simulations of the glass-former 2Ca(NO(3))(2·3KNO(3), CKN, were performed as a function of temperature at pressures 0.1 MPa, 0.5 GPa, 1.0 GPa, and 2.0 GPa. Diffusion coefficient, relaxation time of the intermediate scattering function, and anion reorientational time were obtained as a function of temperature and densitiy ρ. These dynamical properties of CKN scale as ρ(γ)∕T with a common value γ = 1.8 ± 0.1. The scaling parameter γ is consistent with the exponent of the repulsive part of an effective intermolecular potential for the repulsion between the atoms at shortest distance in the equilibrium structure of liquid CKN, Ca(2+), and oxygen atoms of NO(3)(-). Correlation between potential energy and virial is obeyed for the short-range terms of the potential function, but not for the whole potential including coulombic interactions. Decoupling of diffusion coefficient and reorientational relaxation time from relaxation time take place at a given ρ(γ)∕T value, i.e., breakdown of Stokes-Einstein and Debye-Stokes-Einstein equations result from combined thermal and volume effects. The MD results agree with correlations proposed between long-time relaxation and short-time dynamics, lnτ ∝ 1∕, where the mean square displacement concerns a time window of 10.0 ps. It has been found that scales as ρ(γ)∕T above and below the glass transition temperature, so that thermodynamic scaling of liquid dynamics can be thought as a consequence of theories relating short- and long-time dynamics, and the more fundamental scaling concerns short-time dynamical properties.     

Self-assembly snapshots of a 2 × 2 copper(I) grid

Self-assembled 2 × 2 grids have been characterised as high-fidelity species produced when the correct stoichiometric ratios are met, but rarely are the individual steps leading to and from their formation characterised. Here, we present such a study using equilibrium-restricted factor analysis to model a set of UV–vis spectra starting from a bis-bidentate ligand to the assembly of a 2 × 2 grid complex upon titration with 1 equiv. of [Cu(MeCN)₄](PF₆) and to disassembly upon further titration. Intermediate species [CuL₂]⁺, [Cu₂L₃]²⁺, [Cu₃L₂]³⁺ and [Cu₂L]²⁺ are evidenced along the assembly and disassembly pathways. Complementary ¹H NMR titrations are consistent with the rich set of complexes and equilibria involved. Given the nature of the assembly process, the assembly is entropy driven and likely enthalpy driven as well. The disassembly process is both enthalpy and entropy driven according to the standard free energy values derived from the modelling of the spectrophotometric titration data.     

Synthesis, properties, and thermal decomposition of compounds [Co(En)3][Fe(CN)6] · 2H2O and [Co(En)3]4[Fe(CN)6]3 · 15H2O

Binary complex salts, [Co(En)₃][Fe(CN)6] · 2H₂O and [Co(En)₃]₄[Fe(CN)₆]₃ · 15H₂O, are synthesized. The properties of the salts and their thermolysis in air, dihydrogen, and argon are studied. Oxides of the central ions of the binary complex salts are found to be the thermolysis products in an oxidative atmosphere. Solid solutions (intermetallic compounds) CoFe are the thermolysis products in the reductive atmosphere, whereas intermetallides containing considerable amounts of C and N and an impurity of Co and Fe oxides are the thermolysis products in an inert atmosphere. Gaseous thermolysis products in dihydrogen and argon are NH₃, hydrocarbons, and ethylenediamine.     

Mössbauer Spectroscopic Study of xNa2O·5Fe2O3·(95-x)B2O3 Glasses (x=10–35)

A study of xNa₂O·5Fe₂O₃·(95-x)B₂O₃ glasses(x = 10–35) by Mössbauer spectroscopy was carried out in order to elucidate the effect of non-bridging oxygen (NBO) on Mössbauer parameters for Fe³⁺ ions. From the change of the isomer shift and quadrupole splitting, it was found that the Fe³⁺ ions in these borate glasses constitute FeO₄ tetrahedra and play a role of network former. These Mössbauer parameters reflect well the formation of NBO when N₂O contents is larger than 20 mol%. From the measurements of absorption area at low temperature, the _D values for Fe³⁺ ions in 10Na₂O·5Fe₂O₃·85B₂O₃ and 35Na₂O·5Fe₂O₃·60B₂O₃ glasses were determined to be 320 and 289 K, respectively. The decrease of _D value from 320 to 289 K is ascribed to the NBO which was formed by the breaking of -B-O-B- bonds.     

Synthesis and Structural Characterization of Adduct Cu_2(phen)_2·3(FCA)·(ClO_4)·2H_2O

Differentkindsofcopper(II)carboxylateadductshavebeensynthesizedandalsodinuclearcopper(Il)complexeshavebeenearlystUdiedasusefulmodelstoestablishmagneto-structUra1correlationsforspinexchangebetWeenmetalions.CostaIshowedthestructureof[Cu,(ll-OOCFc),(bpy),(ClO')(CH,Oand[Cu,(n-OOCFc),(bpy)(CH,OH),]' .Asfarasweknow,thecopper(II)compoundscontainingFCAandphenhavenotbeenreported.TheligandofFCAwassynthesizedaccordingtothefoIlowingscheme2.3:Asolutioncontainingl98mg(lmmol)ofphenandl5mLofmet…     

Observation and interpretation of 157.5 T internal magnetic field in Fe[C(SiMe3)3]2 coordination compound

The compound Fe[C(SiMe₃)₃]₂ has been prepared and investigated by the means of powder X-ray diffractometry and ⁵⁷Fe Mössbauer spectroscopy. The compound’s unique geometry, in which iron is linearly coordinated by the two C(SiMe₃)₃ ligands, results in a unusual electronic structure of iron, which is visualized as an extreme high hyperfine magnetic field of 157.5(8) T as sensed by the ⁵⁷Fe nucleus at T = 20 K. In order to obtain information on the electronic structure of iron and on the bonds to the ligands, DFT (density functional theory) calculations were carried out on Fe[C(SiMe₃)₃]₂. The high-spin state of iron was found to be energetically favored: an Fe(II) electron configuration of 3d^5.83 4s^0.72 is predicted, where the 4s electron density is only slightly polarized, and most of the unpaired electrons have 3d character. By assuming a linear crystal field, and associated 3d level scheme as a starting point, it is suggested that the extreme high hyperfine magnetic field, observed along with an apparently negative quadrupole splitting, is perpendicular to the C–Fe(II)–C bond axis, and can be decomposed mainly into contact (B _c ≈ 44 T), dipolar (B _d ≈ 14 T), and orbital (B _L ≈ 99 T) hyperfine magnetic field contributions.     

Crystal structure and Raman spectra of [Fe(H2O)6]3+(ClO 4 ? )3·3H2O

Single crystal X-ray diffraction is used to study the structure of colorless crystals isolated from the saturated aqueous solution of trivalent iron perchlorate (TIP) in 67.5% perchloric acid. It is found that the compound crystallizes in the trigonal crystal symmetry; parameters of the hexagonal unit cell: a = b = 16.079(2) ?, c = 11.369(2) ?, ?? = ?? = 90°, ?? = 120°, space group R{ie907-1}(S ₆), Z = 6, ??_calc = 2.021 g/cm³. The structural form of the crystal hydrate is [Fe(H₂O)₆]³⁺(ClO ₄ ^? )₃·3H₂O. The structure contains two independent complex iron cations. Each of them is in the special position {ie907-2}, but retains the regular octahedral structure: average bond lengths are r(Fe-O) = 1.997(1) ?, {ie907-3}O-Fe-O bond angles differ from 90° by only 0.93°. Independent [Fe(H₂O)₆]³⁺ cations form short H-bonds (O??O 2.64 ?) with three crystallization water molecules and somewhat longer H-bonds (O??O 2.73 ?) with three ClO ₄ ^? anions. The ClO ₄ ^? anion is disordered over two positions with occupancies of 0.62(2) and 0.37(2). Both positions correspond to the general position. The outer-sphere crystallization water molecule is characterized by the tetrahedral direction of H-bonds, which it forms with two anions and two independent [Fe(H₂O)₆]³⁺ cations. All water molecules are in the general position. The Raman spectroscopic study of polycrystalline samples reveals weak bands belonging to the internal vibrations of two types of water molecules. The least broad bands are assigned to the transitions of crystallization water molecules whose symmetry is insignificantly lowered by two anion-molecular Hbonds. Anomalously broad bands are assigned to the transitions of a coordinated water molecule whose symmetry is more lowered by intermolecular and anion-molecular H-bonds.     

The electrochemical Peltier heats of Fe(CN) 6 3− /Fe(CN) 6 4− system at 295.15 K

A specially designed thermo-electrochemical calorimeter was applied to measure the electrochemical Peltier heats (EPH) of Fe(CN) ₆ ^3?/4? system at 295.15 K. The curves of the electrode potential changes and temperature changes against time for Fe(CN) ₆ ^3?/4? couple with five groups of different concentrations were obtained under the condition of various constant-current polarizations. The EPH values for the considered electrode reaction are determined to be ?41.31, ?42.73, ?44.28, ?45.87, and ?46.65 kJ mol^?1 at the respective concentrations of 0.125, 0.175, 0.225, 0.275, and 0.300 mol dm^?3; and the EPH and the apparent enthalpy change corresponding to the infinite dilution to be ?37.42 and ?84.10 kJ mol^?1 at 295.15 K, respectively.