Thermal decomposition of [Co(NH3)5Cl]Cl2

The thermal decomposition of [Co(NH₃)₅Cl]Cl₂ was studied under non-isothermal conditions, in dynamic air and argon atmospheres. The kinetics of the particular stages of [Co(NH₃)₅Cl]Cl₂ thermal decomposition were evaluated from the dynamic weight loss data by means of the modified Coats-Redfern method. TheD _n andR _n models were selected as the models best fitting the experimental TG curves. These models suggest that the kinetics and macromechanism of [Co(NH₃)₅Cl]Cl₂ decomposition can be governed by diffusive and/or phase boundary processes. The values of the activation energy,E _a, and the pre-exponencial factor,A, of the particular stages of the thermal decomposition were calculated.     

Thermal decomposition of [Co(NH3)5Cl]Cl2

Simultaneous TG-DTG-DTA studies on [Co(NH₃)₅Cl]Cl₂ under non-isothermal conditions were carried out in dynamic air and argon atmospheres in the temperature range 293–1273 K. Thermogravimetric measurements under quasi-isothermal conditions were also made. On the basis of the experimental data (weight loss, X-ray diffraction, reflectance spectroscopy and chemical analysis), the probable decomposition sequences are presented. The data indicate that the thermal decomposition of [Co(NH₃)₅Cl]Cl₂ occurs in three stages in argon and four stages in air.The changes in the morphology of crystalline [Co(NH₃)₅Cl]Cl₂ powder in the course of its thermal decomposition in air were followed by scanning electron microscopy.

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Zusammenfassung In dynamischer Luft- und ArgonatmosphÄre wurden im Temperaturbereich 293–1273 K unter nichtisothermen Bedingungen simultane TG-DTG-DTA Untersuchungen an [Co(NH₃)₅Cl]Cl₂ durchgeführt, ebenso auch thermogravimetrische Untersuchungen unter quasi-isothermen Bedingungen. Auf der Grundlage der experimentellen Daten (Gewichtsverlust, Röntgendiffraktion, Reflexionsspektroskopie und chemische Analyse) wurde eine wahrscheinliche Zersetzungssequenz erstellt. Es zeigte sich, da\ die thermische Zersetzung in Argon in drei Schritten, in Luft dagegen in vier Schritten verlÄuftDie VerÄnderung der Morphologie kristallinen [Co(NH₃)₅Cl]Cl₂-Pulvers im Verlaufe seiner thermischen Zersetzung in Luft wurde durch Scanning-Elektronenmikroskopie verfolgt.

     

Heat capacity and dual spin-transitions in the crossover system [Fe(2-pic)3]Cl2·EtOH

The heat capacity of [Fe(2-pic)₃]Cl₂·C₂H₅OH Crystal (2-pic: 2-picolylamine) has been measured with an adiabatic calorimeter between 13 and 315 K. Two phase transitions centered at 114.04 and 122.21 K were observed. This finding accords with recent prediction of possible existence of two-step spin-conversion (H. Köppen et al., Chem. Phys. Lett., 91 (1982) 348). The total transition enthalpy and entropy amounted to ΔH = 6.14 kJ mol^?1 and ΔS = 50.59 J K^?1 mol^?1. The transition entropy consists of the magnetic contribution (13.38 J K^?1 mol^?1), the orientational order-disorder phenomenon of the solvate ethanol molecule (8.97) and the change in the phonon system, in particular the change in stretching and deformation vibrations of the metal-ligand (28.24).     

The structure changes and the spin phase transition mechanism of a spin crossover complex, [Fe(2-pic)3]Cl2·EtOH

The crystal structure of the spin crossover complex [Fe(2-pic)₃]Cl₂·EtOH in its high spin state (298, 150 K) and low spin state (90 K) has been determined. The crystals are monoclinic, P2₁/c with Z=4 in the two spin states. Pronounced changes in the FeN bond distance (2.195 A for high spin, 2.013 A for low spin on average) and orientational disorder of the ethanol molecule were observed. The complexes and ethanols are both hydrogen bounded to Cl^? ions.     

Electrochemical and Spectroscopic Studies of Co(CREATININE)2Cl2

The electrochemical behavior of Co(creatinine)₂Cl₂ was investigated by cyclic voltammetry in organic solvents (DMSO and DMF) and in aqueous solution. Analysis of the results indicates that the electroactive species depend on the nature of the solvent. In DMF a single reduction process Co(II)/Co(I) is observed. In DMSO the redox behavior of the complex changes with the scan rate and a two-electron transfer process can be eventually observed. In aqueous solution the complex immediately decomposes giving rise to the aquo-cation. The characteristic peak of the redox couple Cl₂/Cl^? is observed as a consequence of the chloride released from the coordination sphere. Analysis of the electronic spectra gave additional support to the proposed mechanisms. The Co-Cl and Co-N stretching bands were clearly identified in the low frequency region of the IR spectrum.     

Thermal decomposition of the [Co(NH3)6]Cl3, Co[(NH3)4Cl2]Cl,K3[Fe(C2O4)3]3H2O and Fe(CH3COO)3 in argon and air atmosphere

Kinetic parameters (apparent activation energy, reaction order, pre-exponential factor (Z) in the Arrhenius equation) for thermal decomposition of the [Co(NH₃)₆]Cl₃, Co[(NH₃)₄Cl₂]Cl, K₃[Fe(C₂O₄)₃]3H₂O and Fe(CH₃COO)₃ are reported. They have been calculated on the DTA and TG data according to Coats-Redfern's model. Both, decomposition data obtained in argon and in air atmosphere have been considered and the results are compared.

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Zusammenfassung Es werden die kinetischen Parameter (scheinbare Aktivierungsenergie, Reaktionsordnung, prÄexponentieller Faktor (Z) der Arrhenius-Gleichung) der thermischen Zersetzung von [Co(NH₃)₆]Cl₃, [Co(NH₃)₄Cl₂]Cl, K₃[Fe(C₂O₄)₃]3H₂O und Fe(CH₃COO)₃ beschrieben, die entsprechend dem Coats-Redfern-Modell auf der Basis der DTA- und TG-Daten errechnet wurden. Die Zersetzung wurde sowohl in Argon als auch in Luft durchgeführt und die erhaltenen Daten miteinander verglichen.

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Helpful comments from Professor W. Wojciechowski and financial support from Institute for Low Temperatures and Structure Research Polish Academy of Sciences (CPBP 01.12) are greatefully acknowledged.     

Synthesis of Co3O4 nanorod bunches from a single precursor Co(CO3)0.35Cl0.20(OH)1.10

Co₃O₄ nanorods were successfully synthesized from a single precursor via a thermal decomposition and oxidization route. The precursor used was Co(CO₃)_0.35Cl_0.20(OH)_1.10, which was prepared by a hydrothermal reaction using CoCl₂⋅6H₂O with CO(NH₂)₂ at 95–120 °C. Both the precursor and the as-prepared Co₃O₄ were characterized with XRD, TEM, SEM, TGA and XPS. The precursor, as well as Co₃O₄, was found to be composed of nanorods that were radially bunched. The Co₃O₄ nanorods obtained through a thermal treatment at 300 °C for 5 h were found to have a porous structure.     

Unusual spin-transition anomaly in the crossover system [Fe(2-pic)3]Cl2·EtOH

The spin transition in [Fe(2-pic)₃]Cl₂·EtOH (2-pic = 2-picolylamine) has been reinvestigated by Mössbauer spectroscopy and magnetic susceptibility measurements. With both techniques we see a “two-step” spin conversion in the crossover region with transition temperatures at 120.7 and 114.0 K. This has never been reported for any other spin crossover system. The quadrupole splittings for both spin states change abruptly in the range of the transition.     

配合物[Co(benimtacn)Cl2]Cl·3H2O的合成、晶体结构及电化学性质

近年来,带悬臂的1,4,7-三氮环壬烷作为一类直接有效的配体引起了人们的兴趣[1,2],由于悬臂的柔顺性和多样性,这类配体可能形成非常有趣且稳定的配合物[3￣5]。特别是选择性悬臂配体形成的配合物,作为酶模型物时,容易形成催化活性空位[6￣8];悬臂较少,空间位阻较小的配体在形成配合物时易自组装成桥连双核二聚体[9,10]。     

Crystal structure of tris(ethylenediamine)cobalt(III) (aqua)hexachloromercurate(II) chloride [Co(En)3]2[Hg2(H2O)Cl6]Cl4

The compound [Co(En)₃]₂[Hg₂(H₂O)Cl₆]Cl₄ (I, En is ethylenediamine) has been synthesized and studied by X-ray diffraction. The crystals of I (a = 21.8745(14) Å, b = 10.6008(6) Å, c=15.4465(12) Å, space group Pna2₁) consist of tris(ethylenediamine)cobalt(III) complexes (the unit cell contains two [Co(En)₃]³⁺ cations of opposite chirality). [Hg₂(H₂O)Cl₆]^2? anions, and isolated chloride ions. The complex anion consists of the tetrahedral [HgCl₄]^2? group (Hg-Cl, 2.44–2.56 Å) and the hydrated molecule [Hg(H₂O)Cl₂] (Hg-Cl, 2.301 and 2.308 Å; Hg-O, 2.788 Å) combined by weak Hg-Cl interactions (2.915 and 3.220 Å).     

Double-salt formation in crystal structures containing [Co(en)3]Cl3

The structures of three racemic double salts of [Co(en)₃]Cl₃ (en is ethane-1,2-diamine, C₂H₈N₂), namely, bis[tris(ethane-1,2-diamine-κ²N,N′)cobalt(III)] hexaaquasodium(I) heptachloride, [Co(en)₃]₂[Na(H₂O)₆]Cl₇, bis[tris(ethane-1,2-diamine-κ²N,N′)cobalt(III)] hexaaquapotassium(I) heptachloride, [Co(en)₃]₂[K(H₂O)₆]Cl₇, and ammonium bis[tris(ethane-1,2-diamine-κ²N,N′)cobalt(III)] heptachloride hexahydrate, (NH₄)[Co(en)₃]₂Cl₇·6H₂O, have been determined, and the structural similarities with the parent compound, tris(ethane-1,2-diamine-κ²N,N′)cobalt(III) trichloride tetrahydrate, [Co(en)₃]Cl₃·4H₂O, are highlighted. All four compounds crystallize in the trigonal space group Pc1. When compared with the parent compound, the double salts show a modest increase in the unit-cell volume. The structure of the chiral derivative [Λ-Co(en)₃]₂[Na(H₂O)₆]Cl₇ has also been redetermined at cryogenic temperatures (120 K) and the disorder noted in a previous report has been accounted for.     

Co(NH3)2Cl2 and Co(ND3)2Cl2: Order‐Disorder Behaviour of N(H, D)3 and Antiferromagnetic Structure

Diammine cobalt(II) chloride, Co(N(H, D)₃)₂Cl₂ was prepared by decomposition of the corresponding hexaammines at 120 °C in dynamical vacuum. Crystal structures and magnetic properties of these materials were characterised by X‐ray and neutron powder diffraction, and heat capacity measurements. At ambient temperatures Co(N(H, D)₃)₂Cl₂ crystallises in the Cd(NH₃)₂Cl₂ type structure: space group Cmmm, Z = 2, a = 8.0512(2) Å, b = 8.0525(2) Å, c = 3.73318(9) Å (X‐ray data of the H compound). This structure consists of chains of edge‐sharing octahedra [CoCl_4/2(NH₃)₂] running along the c‐axis. Neutron diffraction confirms that that the ND₃ groups are rotationally disordered at ambient temperatures. At 1.5 K and 20 K neutron diffraction data reveal rotational ordering of the ND₃ groups leading to doubling of the c‐axis and to Ibmm symmetry: a = 7.9999(6) Å, b = 7.9911(5) Å, c = 7.4033(3) Å (Z = 4, values for T = 1.5 K). Furthermore, antiferromagnetic ordering is present at these temperatures. It is caused by a ferromagnetic coupling of the magnetic moments at Co²⁺ (3.60(5) μ_B at 1.5 K, 3.22(5) μ_B at 20 K) along the octahedra chains [CoCl_4/2(NH₃)₂] and antiferromagnetic coupling between neighbouring chains. According to heat capacity measurements the phase transition antiferromagnetic‐paramagnetic takes place at T_N = 26 K.     

Die darstellung von [(CH3)3PRu(CO)2Cl2]2 und [(Ch3)3P]2Ru(CO)2Cl2; Eine berichtigung zu: Die alkoholyse des triethylsilans katalysiert von [(Ch3)3P]2Ru(CO)2Cl2

The ruthenium(II) complex used as a catalyst in reactions of alcohols and Et₃SiH proved to be the dimer [(CH₃)₃PRu(CO)₂Cl₂]₂ and not the complex [(CH₃)₃P]₂ Ru(CO)₂Cl₂. Both complexes were prepared, characterized and their catalytic properties were compared.     

Darstellung und Kristallstruktur von Tris(äthylendiamin)kobalt(III)-trichlorostannat(II)-dichlorid, [Co(en)3][SnCl3]Cl2

Preparation and Crystal Structure of Tris(ethylenediamine) cobalt(III)-trichlorostannate(II)-dichloride, [Co(en)₃] [SnCl₃]Cl₂ The title compound has been prepared from [Co(en)₃]Cl₃ and SnCl₂ · 2H₂O in aqueous HCl solution. It crystallizes in the orthorhombic space group Pbca, with a = 21.906(7), b = 10.607(3), c = 15.356(7) Å. The crystal structure has been determined from 1606 independent reflections by Patterson snd Fourier syntheses, and has been refined by least squares methods to R = 0.074. The [Co(en)₃]³⁺ ion is found to have the conformation of Λ(δδλ) resp. Δ(λλδ). The structure of the [SnCl₃]^? ion corresponds to a distorted tetrahedron, in which one site is occupied by the stereochemically active 5s electron pair. The following Sn? Cl distances have been found 2.493(7), 2.492(5), 2.479(7) Å, the distances of the two anionic Cl atoms from Sn are >4 Å.     

Crystal Structure,Magnetic Properties,and Electronic Structure of Ni(NCNH2)4Cl2 and Co(NCNH2)4Cl2

The crystal structures of Ni(NCNH₂)₄Cl₂ and Co(NCNH₂)₄Cl₂, the first complexes with cyanamide as a neutral ligand, have been determined from single crystal data (Im3m, Z = 6, a = 1259.3(2) pm, R₁ = 0.0245 for Ni(NCNH₂)₄Cl₂ and a = 1266.3(2) pm, R₁ = 0.0241 for Co(NCNH₂)₄Cl₂; both 329 intensities and 23 parameters). Ni²⁺ and Co²⁺ are octahedrally coordinated by four equatorial H₂NCN molecules and two axial chloride ions, and the 20 and 19 electron octahedral complexes are connected by a network of hydrogen bonds. The cyanamide ligands are slightly bent (166°), and the two N–C distances are 112 and 133 pm. Ni(NCNH₂)₄Cl₂/Co(NCNH₂)₄Cl₂ are Curie paramagnets with two/three unpaired electrons.     

Crystal structure of the new compound Co6(TeO3)2(TeO6)Cl2

The new compound Co₆(TeO₃)₂(TeO₆)Cl₂ has been isolated during an investigation of the system CoO:CoCl₂:TeO₂. The new compound is deep purple in color and crystallizes in the tetragonal system, space group P4₂/mbc, a=8.3871(7) Å, c=18.5634(19) Å, Z=4. The Co(II) ions have octahedral [Co1O₆] and tetrahedral [Co2O₃Cl] coordinations. Tellurium is present both as Te(IV) with a tetrahedral [Te1O₃E] coordination, where E is the 5s² lone-pair and as Te(VI) with an octahedral [Te2O₆] coordination. The structure is made up of intersecting layers of tetrahedra forming channels comprising octahedra chains that run along the c-axis. The new compound is the first cobalt tellurium oxochloride described.     

Crystal Structure of [M(NH3)5Cl]2[IrCl6]Cl2 (M = Co, Rh, Ir) Binary Complex Salts

Binary complex salts of M(NH₃)₅Cl]₂[IrCl₆]Cl₂ composition, where M = Co(III), Rh(III), or Ir(III), have been studied. All phases are isostructural with [M(NH₃)₅Cl]₂[PtCl₆]Cl₂ complexes [M = Rh(III) and Ir(III)]; Xray structural and crystallochemical analysis have been performed.     

Crystal structures of bis(diethylenetriamine)cobalt(III) Heptachlorodimercurate(II)mer-[Co(Dien)2]Hg2Cl7 and (diethylenetriamine)glycylglycinato(1-) cobalt(III) hexachlorodimercurate(II) [Co(Dien)HGlygly]Hg2Cl6

An X-ray diffraction analysis was performed for crystalline [Co(Dien)₂]Hg₂Cl₇ (a = 14.452(2), b = 9.831(1), c = 15.967(2) åΒ = 97.17(1)?, space group P2₁/c, Z = 4) and [Co(Dien)HGlygly]Hg₂Cl₆ (a = 7.693(1), b = 14.439(2), c = 19.961(2) å, Β = 100.31(1)?, space group P2₁ Z = 2), where Dien is diethylenetriamine and HGlygly is the glycylglycine anion [H₂NCH₂C(OH) = NCH₂CO₂]. The anionic moiety is represented by isolated centrosymmetric ions [Hg₄Cl₁₄]_6- in the former and by infinite chains [Hg₂Cl₆] _n ^2n- in the latter (the chain is composed of two alternating vertex-sharing nonequivalent tetrahedral groups HgCl₄. In the cobalt(III) complex cations, the extreme donating atoms of the Dien and HGlygly ligands are in the trans positions of the coordination octahedron.     

An electrical conductivity (EC) study of the thermal dissociation of [Co(NH3)6]X3 and [Co(en)3]X3 complexes

The thermal dissociation of the [Co(NH₃)₆]X₃ (X = Cl^?, Br^?, I^?, and NO^?₃), [Co(en)₃]X₃ (X = Cl^?, Br^?, I^?, NO^?₃, HSO^?₄ and $\text{1}\text{2}$ C₂O^2?₄), cis- [Co(en)₂Cl₂]Cl, and trans-[Co(en)₂ClBr]NO₃ complexes was investigated by an electrical conductivity (EC) technique. During the thermal dissociation reactions, liquid or semi-liquid phases are formed which cause large increases in the EC of the compound. The effect of concentration of the complex in a matrix medium as well as the composition of the matrix material on the EC curves were also determined.     

Selenious Acid as a Ligand: Molecular and Crystal Structure of [Co(H2O)2Cl2(H2SeO3)2]

[Co(H₂O)₂Cl₂(H₂SeO₃)₂] (monoclinic, P2₁/c, Z = 2, a = 519.82(5), b = 1462.6(1), c = 643.09(7) pm, β = 92.51(1)°, R_all = 0.0583) was obtained from CoCl₂ and H₂SeO₃ as purple plate–shaped single crystals. In the compound, the Co²⁺ ions are octahedrally coordinated by two Cl^? ions, two H₂O molecules, and two monodentate H₂SeO₃ molecules, leading to neutral complexes [Co(H₂O)₂Cl₂(H₂SeO₃)₂]. They are connected by hydrogen bonds involving both chlorine and oxygen atoms as acceptor atoms.