Preparation of sodium ferrite from the thermolysis of sodium tris(maleato/fumarato)ferrates(III)

Thermal decomposition of sodium tris(maleato)ferrate(III) hexahydrate, Na₃[Fe(C₄H₂O₄)₃]·6H₂O and sodium tris(fumarato)ferrate(III) heptahydrate, Na₃[Fe(C₄H₂O₄)₃]·7H₂O has been studied upto 973 K in static air atmosphere employing TG, DTG, DSC, XRD, Mössbauer and infrared spectroscopic techniques. Dehydration of the maleate complex is complete at 455 K and the anhydrous complex immediately undergoes decomposition till α-Fe₂O₃ and sodium carbonate are formed at 618 K. In the final stage of remixing of cations, a solid state reaction between α-Fe₂O₃ and sodium carbonate leads to the formation of α-NaFeO₂ at a temperature (773 K) much lower than for ceramic method. Almost similar mode of decomposition has been observed for the fumarate complex. A comparison of the thermal stability shows that the fumarate precursor decomposes at a higher temperature than the maleate complex due to the trans geometry of the former.     

A cyano-bridged hetero-tetranuclear [Sm2(o-phen)2(DMF)6(H2O)2(μ-CN)4Fe2(CN)8] · 5H2O · CH3OH: synthesis,structure, Mössbauer spectrum,and magnetism

Two new hetero-tetranuclear complexes, [Sm₂(o-phen)₂(DMF)₆(H₂O)₂(µ-CN)₄Fe₂(CN)₈]·;5H₂O·;CH₃OH (1) and [Sm₂(o-phen)₂(DMF)₆(H₂O)₂(µ-CN)₄Co₂(CN)₈]·;5H₂O (2), have been prepared from reaction of SmCl₃·;6H₂O, K₃[Fe(CN)₆]·;3H₂O or K₃[Co(CN)₆], and o-phen in methanol/DMF, and characterized. The structure of 1 consists of a cyano-bridged discrete cyclic tetranuclear complex in which the Sm(III) and Fe(III) centers are linked by four CN groups. Mössbauer spectrum of ⁵⁷Fe indicates that both Fe(III) atoms in 1 have the same low-spin (S?=?1/2) electronic ground state. From comparison of the magnetic data of 1 and 2, at low temperature for 1 indicates weak ferromagnetic coupling between Sm(III) and Fe(III).     

Thermal studies on oxalate complexes. II. Complexes of iron (III) and chromium (III)

The decomposition of solid K₃[Fe(C₂O₄)₃] · 2 H₂O and K₃[Cr(C₂O₄)₃] · 3 H₂O has been studied using TGA and DSC. After dehydration, the chromium compound was found to decompose by the loss of CO in two steps, the loss of CO₂ and additional CO, and finally the loss of CO₂. The final product appears to be either K₃CrO₃ or the mixed oxides of chromium and potassium. Kinetic parameters and enthalpy data are presented for these reactions. In the case of K₃[Fe(C₂O₄)₃] · 2 H₂O, dehydration is followed by the loss of CO₂ and CO, CO₂ alone, and finally CO. The final product appears to be a basic carbonate of the type K₃[FE(O)₂(CO₃)]. Kinetic and thermal data are presented for most of these decomposition reactions.     

Copper(II) complexes with pyridine-2,6-dicarboxylic acid from the oxidation of copper(I) iodide

Via an oxidation reaction of Cu(I) iodide with pyridine-2,6-dicarboxylic acid (H₂L) in DMF three copper(II) complexes, [(CH₃)₂NH₂]₂[CuL₂] (1), K₂[CuL₂]?H₂L?H₂O (2) and [Cu(L)(H₂O)]_n (3), were synthesized and characterized. The structures of 1–3 were determined by single crystal X-ray diffraction studies. In-situ DMF decomposition produces dimethylamine base under solvothermal conditions and a proton transfer reaction takes place for the complex formation of 1. 3-D networks are stabilized in 1 and 2 via hydrogen bonds. Complex 3 is a 1-D coordination polymer with Cu-O semi-coordination bonds. Thermal decomposition of the complexes results in the corresponding metal oxides. Also, the electrochemical behavior of 1 was determined to be a metal-centered and diffusion-controlled, one-electron reduction process.     

Crystal structure and spectroscopic behavior of three new tris-oxalatoferrate(III) salts

A new general synthetic procedure for preparation of Na₃[Fe(C₂O₄)₃]·5H₂O (1), Rb₃[Fe(C₂O₄)₃]·3H₂O (2), and Cs₃[Fe(C₂O₄)₃]·2H₂O (3) was developed. The crystal structures of these salts have been determined by single crystal X-ray diffraction. Salt 1 crystallizes in the monoclinic space group C2/c with Z = 8, salt 2 in P2₁/c with Z = 4, and salt 3 in P2₁/n with Z = 4. The three new salts and K₃[Fe(C₂O₄)₃]·3H₂O, prepared for comparative purposes, were further characterized by infrared and ⁵⁷Fe-Mössbauer spectroscopy. These spectra are discussed in comparison with those of related oxalato complexes.     

Partial molar volumes and partial molar adiabatic compressibilities of potassium trioxalato complexes of Al(III), Fe(III), Co(III), and Cr(III) between 15° and 35°C

The apparent and limiting apparent molal volumes of dilute aqueous solutions of K₃[Al(ox)₃] · 3H₂O, K₃[Fe(ox)₃] · 3H₂O, K₃[Co(ox)3] · 3H₂O, and K₃[Cr(ox)₃] · 3H₂O complexes were determined from density data measured at 15°, 25°, and 35°C. The apparent and limiting apparent molal adiabatic compressibilities of these complexes were determined from measured ultrasonic sound velocities at 15°, 25°, and 35° in dilute aqueous solutions. The volume change associated with complex formation is discussed in terms of the nature of the coordinate bond and the overall hydration behavior of these complexes.     

Coordination complexes of iron(III) with 3-hydroxy-2(1H)-pyridinone, 2,3-dihydroxybenzoic acid and 3,4-dihydroxybenzoic acid: preparation and characterization in the solid state

Summary The synthesis and study of a number of new iron(III) complexes of the ligands 3-hydroxy-2(1H)-pyridinone (3,2-opoH), 2,3-dihydroxybenzoic acid (2,3-dhbH₃) and 3,4-dihydroxybenzoic acid (3,4-dhbH₃) are described. These complexes have the formulae [Fe(3,2-opo)₂Cl]·PrⁿOH, K[Fe(2,3-dhbH)₂(H₂O)₂], [Fe(2,3-dhb)(H₂O)₂], K[Fe-(3,4-dhbH)₂(H₂O)₂], [Fe(3,4-dhb)(H₂O)₂] and K₆[Fe(3,4-dhb)₃]·3H₂O. The complexes were characterized by elemental analyses. X-ray powder patterns, t.g.a./d.t.g. techniques, magnetic susceptibilities and spectroscopic (u.v.-vis., i.r. and variable-temperature ⁵⁷Fe-M?ssbauer) studies. Monomeric octahedral structures are assigned for the 1∶2 2,3-dhbH²⁻ complex and the 1:3 3,4-dhb³⁻ compound. Dinuclear and/or oligonuclear structures are tentatively proposed for the remaining complexes in the solid state. In [FeL(H₂O)₂] (L³⁻ = 2,3-dhb³⁻ or 3,4-dhb³⁻), iron(III) appears to be 5-coordinate. Both oxygens of 3,2-opo⁻ participate in coordination, while the dihydroxybenzoato ligands exhibit various coordination modes, depending mainly on the positions of the hydroxy groups, their anionic charge and the ligand∶metal molar ratio used.     

Syntheses and Crystal Structures of Two Ion Pair Complexes, [Ru(bpy)3]2[Fe(CN)6]I · 7H2O and [Ru(bpy)3]- [Fe(CN)5NO]CH3OH · H2O

Two ion pair complexes, [Ru(bpy)₃]₂[Fe(CN)₆]I [sdot] 7H₃O (1) and [Ru(bpy)₃][Fe(CN)₅NO](CH₃OH) [sdot] H₂O (2) (bpy = 2,2-bipyridine) have been synthesized and structurally characterized. X-Ray crystallographic structures of 1 and 2 both show Fe(III) and Ru(II) in distorted octahedral environments. In both complexes, H-bonding interactions between an uncoordinated water molecule and the nitrogen atom of a cyano group exist.     

Mössbauer and X-ray crystallographic studies of etraalkylammonium hexacyanoferrates(III)

A hexacyanoferrate(III) salt [N(C₂H₅)₄]₃[Fe(CN)₆]^.5H₂O (1)crystallized in a monoclinic space group (P2₁, Z = 2) with the nearest neighboring Fe-Fe distance of 8.20 Åound 1 distinctly showed magnetically-relaxed ⁵⁷Fe Mössbauer spectra below ca. 40 K. The Mössbauer line width at 4.2 K was much larger than that of K₃[Fe(CN)₆], which is ascribable to the long Fe-Fe distance in 1. Further broadened spectra were observed for [N(n-C₄H₉)₄]₃[Fe(CN)₆]^.xH₂O (2).     

Magnetic Properties of M3[Fe(Cn)6]2Xh2O (M = Co (II), Ni(II), Cu(II), Zn(II))

Compounds of the type M₃[Fe(CN)₆]₂XH₂O (M = Co(II), Ni(II), Cu(II), and Zn(II)) were prepared and magnetic properties of their powders were investigated by means of EPR spectra, Mössbauer effect and magnetic susceptibility measurements. The temperature dependence of the magnetization for the complexes Co₃[Fe(CN)₅]₂- 10H₂O, Ni₃[Fe(CN)₆]₂-10H₂O and Cu₃[Fe(CN)₆]₂-4H₂O revealed that below the critical temperatures 15, 22 and 20 K respectively, these complexes have zero-field magnetization. The magnetic hysteresis at 10 K for Co(II), Ni(II) and Cu(II) complexes was observed. Mössbauer spectra at 4.2 K for the compounds are discussed.     

Thermisches Verhalten von Caesiumchloroferraten(III) und Caesiumchloroferrat(III)-Hydraten. II. Die Rehydratation der Zersetzungsprodukte von Cs3[FeCl6] – Eine ramanspektroskopische Untersuchung unter definierter Wasserdampfatmosphäre [1]

The Thermal Behaviour of Caesiumchloroferrates(III) and Caesiumehloroferrate(III) Hydrates. II. The Rehydration of Decomposition Products of Cs₃[FeCl₆] — A Raman Spectroscopic Study under Definite Atmosphere of Water Vapour Cs₃[FeCl₆] formed by dehydration of Cs₃[FeCl₆] · H₂O at about 160°C does not change at normal atmosphere within 3 till 4 hours. Rehydration under the vapour pressure of the eliminated water yields the monohydrate in nearly the same time. In the same manner rehydration of the solid mixture of Cs[FeCl₄] and 2 CsCl formed by thermal decomposition of the metastable Cs₃[FeCl₆] (280°C) produces the intermediates Cs₃[Fe₂Cl₉] and Cs₂[Fe(H₂O)Cl₅] in mixtures with CsCl and, finally, Cs₃[FeCl₆] · H₂O. The formation of Cs₃[Fe₂Cl₉] from Cs[FeCl₄] and CsCl is accelerated by water. The reaction cycle has been studied using Raman and IR spectroscopy. The results will be discussed with respect to thermoanalytical data.     

Reactions of 2-(1-carboxyl-2-hydroxyphenyl)thiazolidine with chromium(III) salts leading to newer synthesis of chromium(III) complexes

Reactions of 2-(L-carboxyl-2-hydroxyphenyl)thiazolidine with different chromium(III) salts [CrCl₃?·?6H₂O, K₃[Cr(SCN)₆], NH₄[Cr(NH₃)₂(SCN)₄]?·?H₂O, [Cr(urea)₆]Cl₃?·?3H₂O and [Cr(CH₃COO)₂H₂O]₂] under varied reaction conditions afforded many new mixed-ligand chromium(III) complexes. The ligand is a tridentate dibasic NSO donor except for complexes 1 and 4 where two moles of the ligand are present for each molecule of complex, one functioning as a dibasic tridentate (NSO) and the other as a monobasic bidentate (NS) (phenolic OH and carboxylic COOH groups remaining uncoordinated). The complexes have been characterized by elemental analyses, magnetic susceptibilities, molar conductances, molecular weights and spectroscopic (IR, Uv-vis) data. The ligand field parameters and NSH Hamiltonian parameters suggest tetragonal geometries of the complexes.     

On the Lanthanide Ferrocyanides KLnFe(II)(CN)6·xH2O (Ln=La-Lu): Characterization and Thermal Evolution

The properties of a series of lanthanide hexacyanoferrate(II) n-hydrates were studied by thermal analysis, IR spectroscopy and X-ray diffraction. Thermal analysis results show that there are three kinds of complexes in this series, KLn[Fe(CN)₆]·4 H₂O (Ln=La-Nd), KSm[Fe(CN)₆]·3H₂O and KLn[Fe (CN)₆]·3.5H₂O (Ln=Eu-Lu). On the basis of IR spectra, only two different types of complexes show obvious differences. Indeed for the tetrahydrates, there is one OH stretching band; on the other hand, for the samarium phase and the 3.5 hydrates a splitting of HOH stretching mode is observed. The splitting of the H₂O band is correlated to a symmetry modification. The crystal structures of the three complexes KLn[Fe(CN)₆]·3.5H₂O (Ln=Eu, Er and Lu) were determined; they belong to orthorhombic symmetry (space group Cmcm). Heat-treated powders have been investigated by X-ray analysis which show the formation of thin needles of LnFeO₃ at 600°C.     

Synthesis and spectroscopic characterization of new metal(II) complexes with methionine sulfoxide

Methionine sulfoxide complexes of iron(II) and copper(II) were synthesized and characterized by chemical and spectroscopic techniques. Elemental and atomic absorption analyses fit the compositions K₂[Fe(metSO)₂]SO₄·H₂O and [Cu(metSO)₂]·H₂O. Electronic absorption spectra of the complexes are typical of octahedral geometries. Infrared spectroscopy suggests coordination of the ligand to the metal through the carboxylate and sulfoxide groups. An EPR spectrum of the Cu(II) complex indicates tetragonal distortion of its octahedral symmetry. ⁵⁷Fe Mössbauer parameters are also consistent with octahedral stereochemistry for the iron(II) complex. The complexes are very soluble in water.     

Determination of kinetic parameters of inorganic metalporphyrins

The thermal properties of four heteropoly complexes α-K₃H₃[SiW₁₁Ni(H₂O)O₃₉]·11.5H₂O (I), α-K₃H₂[SiW₁₁Fe(H₂O)O₃₉]·9H₂O (II), α-[(C₄H₉)₄N]_3.5H_1.5[SiW₁₁Fe(H₂O)O₃₉]·4.5H₂O (III) and α-[(C₄H₉)₄N]_3.5H_2.5[SiW₁₁Cu(H₂O)O₃₉]·6H₂O (IV) were studied by means of TG, DTA and DSC. The activation energy and reaction order of the thermal decomposition reaction of these complexes have been calculated.

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Zusammenfassung Mittels TG, DTA und DSC wurden die thermischen Eigenschaften der vier heteropolaren Komplexe α-K₃H₃[SiW₁₁Ni(H₂O)O₃₉]·11.5H₂O (I), α-K₃H₂[SiW₁₁Fe(H₂O)O₃₉]·9H₂O (II), α-[(C₄H₉)₄N]_3.5H_1,5[SiW₁₁Fe(H₂O)O₃₉]·4.5H₂O (III) und α-[(C₄H₉)₄N]_3.5H_2,5 [SiW₁₁Cu(H₂O)O₃₉]·6H₂O (IV) untersucht. Die Aktivierungsenergie und Reaktionsordnung der thermischen Zersetzungsreaktion dieser Komplexe wurde berechnet.

     

Mössbauer effect studies on alkali tris(maleato) ferrates(III)

Mössbauer spectra of alkali tris(maleato) ferrates(III), i.e., M₃[Fe(C₂H₂C₂O₄)₃]·nH₂O [M=Li, Na, K, Cs] at 300 K display a doublet. The Mössbauer parameters indicate these complexes to be high spin with octahedral symmetry. The isomer shift shows a decreasing trend with the increase in electronegativity/polarizing power of the substituent cation (Li⁺, Na⁺, K⁺, Cs⁺). A linear correlation between isomer shift values and the (Fe?O) stretching frequencies has also been observed.     

Thermoanalytical and spectroscopic studies on hydrazinium lighter lanthanide complexes of 2-pyrazinecarboxylic acid

The new hydrazinium lanthanide metal complexes of 2-pyrazinecarboxylic acid (HpyzCOO) of the formulae (N₂H₅)₂[Ln(pyzCOO)₅] · 2H₂O (1), where Ln = La or Ce and (N₂H₅)₃[Ln(pyzCOO)₄(H₂O)] · 2NO₃ (2), where Ln = Pr, Nd, Sm or Dy have been synthesized and characterized by physico-chemical methods. The IR absorption bands of N–N stretching at 960 cm⁻¹ unambiguously prove the existence of N₂H₅ ⁺ ions. The bonding parameters β, b^1/2, % δ and η, have been calculated from the electronic spectroscopic (hypersensitive) bands of Pr(III) and Nd(III) complexes. All the complexes undergo endothermic followed by exothermic decomposition to leave the respective metal oxides as the end products. However, the DTA of the complexes 2 demonstrate rather sharp peak than the complexes 1, owing to overwhelming exothermicity, which may be due to the loss of both hydrazine and nitrate moieties in the same step. The X-ray powder diffraction studies reveal the existence of isomorphism among the member complexes.     

Influence of the intermolecular interaction on photo-induced spin-transition of [Fe(R-pap)<Subscript>2</Subscript>]X

Summary Iron(III) spin-crossover complexes [Fe(pap)₂]ClO₄^. H₂O (1), [Fe(pap)₂]BF₄^. H₂O (2), [Fe(pap)₂]PF₆^. CH₃OH (3), [Fe(CH₃-pap)₂]ClO₄^. H₂O (4), [Fe_0.5Al_0.5(pap)₂]ClO₄^. CH₃OH (5) and [Fe_0.25Al_0.75(pap)₂] ClO₄^. CH₃OH (6)were prepared andthe spin transition behaviors of the complexes have been studied from magnetic susceptibility and M?ssbauer spectroscopy measurements. The magnetic properties of light-induced metastable state are measured using Hg-Xe light source. T_1/2is temperature at which the populations of the high-spin and low-spin species are fifty-fifty. Metastable HS is produced by light irradiation at 5 K. T(LIESST) is the temperature at which the populations of the metastable high-spin species decrease to one half and cooperativity factor Cis defined as the parameter which presents the strength of cooperativity. The value of T(LIESST) decreases as T_1/2increases and the plots of T(LIESST) vs. Cshow linear correlation. The effect of cooperativity of the complexes on the relaxations in solid was confirmed for the iron(III) complexes.     

Ru(III) complexes derived from N -methyl derivatives of glycine and 1,3-propylenediamine- N,N ′-diacetato ligands and their activities against HeLa,K562 cell lines and human PBMC

Ruthenium(III) complexes formulated as K₂[Ru(sar)Cl₄]·H₂O and K[Ru(dmgly)₂Cl₂]·3H₂O containing bidentate chelates N-methylglycine (sarcosine, sar) or N,N-dimethylglycine (dmgly) as well as K[Ru(pdda)Cl₂]·2.5H₂O complex with tetradentate 1,3-propylenediamine-N,N′-diacetato were synthesized. The complexes were obtained by direct reaction of ruthenium(III) chloride with the corresponding bidentate or tetradentate ligand followed by addition of a base (KOH). These new complexes were characterized by elemental analysis, IR and electronic absorption spectroscopy. To assess selectivity in the antitumor action of these complexes, their antiproliferative activities against human adenocarcinoma HeLa cells, human myelogenous leukemia K562 cells, human breast carcinoma MDA-MB-361 and MDA-MB-453 cells and normal immunocompetent PBM cells were determined.     

Complex Carbonates of Iron(III)

The complex carbonates of iron(III) are shown to be anionic in nature. The solutions containing these complexes show a maximum absorbance at 460 nm. The complex carbonates of iron(III), viz., (i) K₆[Fe₂(OH)₂(CO₃)₅] · H₂O, — (ii) Na₂[Fe₃O₂(OH)₃(CO₃)₂], — (iii) K[Co(NH₃)₆]₂[Fe₃(OH)₄(CO₃)₆], — (iv) K₅[Co(NH₃)₆]₃[Fe₃(OH) ₄(CO₃)₆]₂, — (v) K[Co(NH₃)₆][Fe₂(OH)₄(CO₃)₃], and (vi) NH₄[Co(NH₃)₆][Fe₂(OH)₄(CO₃)₃] are isolated and studied by thermogravimetry. The infrared spectra of these compounds are recorded and probable band assignments made. Besides, the reaction between KHCO₃ and Fe(NO₃)₃ was studied through chemical and physicochemical methods.