Changes in electronic,magnetic and bonding properties from Zr2FeH5 to Zr3FeH7 addressed from ab initio

Potential hydrogen storage ternaries Zr₃FeH₇ and Zr₂FeH₅, are studied from ab initio with the purpose of identifying changes in electronic structures and bonding properties. Cohesive energy trends: E_coh. (ZrH₂) > E_coh. (Zr₂FeH₅) > E_coh. (Zr₃FeH₇) > E_coh. (hypothetic-FeH) indicate a progressive destabilization of the binary hydride ZrH₂ through adjoined Fe so that Zr₃FeH₇ is found less cohesive than Zr₂FeH₅. From the energy volume equations of states EOS the volume increase upon hydriding the intermetallics leads to higher bulk moduli B₀ explained by the Zr/Fe–H bonding. Fe–H bond in Zr₂FeH₅ leads to annihilate magnetic polarization on Fe whereas Fe magnetic moment develops in Zr₃FeH₇ identified as ferromagnetic in the ground state. These differences in magnetic behaviors are due to the weakly ferromagnetic Fe largely affected by lattice environment, as opposed to strongly ferromagnetic Co. Hydrogenation of the binary intermetallics weakens the inter-metal bonding and favors the metal–hydrogen bonds leading to more cohesive hydrides as with respect to the pristine binaries. Charge analyses point to covalent like Fe versus ionic Zr and hydrogen charges ranging from covalent H^−0.27 to more ionic H^−0.5.     

Thermal analysis of the Bi2O3-Y2O3-ZrO2 pigments

The synthesis of new compounds based on Bi₂O₃ is investigated because they can be used as new colour inorganic pigments. Chemical compounds of the Bi_2-xY_x/2Zr_3x/₈O₃ type were synthetised. The host lattice of these pigments is Bi₂O₃ that is doped by Y³⁺ and Zr⁴⁺ ions. The incorporation of doped ions provides interesting colours and contributes to a growth of the thermal stability of these compounds. The simultaneous TG-DTA measurements were used for determination of the temperature region of the pigment formation and thermal stability of pigments. This paper also contains the results of the pigment characterization by X-ray powder diffraction and their colour properties.     

Thermal analysis of the Bi2O3-Er2O3-Zro2 pigments

The synthesis of new compounds based on Bi₂O₃ is investigated because they can be used as new ecological inorganic pigments. Chemical compounds of the Bi_2−xEr_x/2Zr_3x/8O₃ type were synthetized. The host lattice of these pigments is Bi₂O₃ that is doped by Er³⁺ and Zr⁴⁺ ions. The incorporation of doped ions provides interesting colours and contributes to a growth of the thermal stability of these compounds. The simultaneous TG-DTA measurements were used for determination of the temperature region of the pigment formation and thermal stability of pigments. This paper also contains the results of the pigment characterization by X-ray powder diffraction and their colour properties.     

Na1－xZr2－xNbxP3O12系列化合物的水热晶化研究

采用水热晶化反应，制备出传统需要高大相反合成的掺杂，ＮＡＳＩＣＯＮ化合物Ｎａ１－ｘＺｒ２－ｘＮｂｘＰ３Ｏ１２（０＜Ｘ＜１），并应用ＸＲＤ，ＩＲ方法对产物的晶体结构进行了研究。表明水热晶化产物是纯的物相并具有与ＮａＺｒ２Ｐ３Ｏ１２相同的结构，固体＾３１ＰＮＭＲ研究证实Ｎｂ＾５＋部分取代了Ｚｒ＾４＋所在位置，参与骨架的组成，并统计分布于结构中，水热晶化产物与固相反应产物具有相同的离子电导性能。     

Phase formation in the ZrO(NO<Subscript>3</Subscript>)<Subscript>2</Subscript>-H<Subscript>3</Subscript>PO<Subscript>4</Subscript>-CsF-H<Subscript>2</Subscript>O system at low concentration of the phosphorus-containing component

The ZrO(NO₃)₂-H₃PO₄-CsF-H₂O system was studied at 20°C along the section at a molar ratio of PO₄³⁻/Zr = 0.5 (which is of the greatest interest in the context of phase formation) at ZrO₂ concentrations in the initial solutions of 2–14 wt % and molar ratios of CsF: Zr = 1−6. The following compounds were isolated for the first time: crystalline fluorophosphates CsZrF₂PO₄ · H₂O, amorphous oxofluorophosphate Cs₂Zr₃O₂F₄(PO₄)₂ · 3H₂O, and amorphous oxofluorophosphate nitrate CsZr₃O_1.25F₄(PO₄)₂(NO₃)_0.5 · 4.5H₂O. The compound Cs₃Zr₃O_1.5F₆(PO₄)₂ · 3H₂O was also isolated, which forms in a crystalline or glassy form, depending on conditions. The formation of the following new compounds was established: Cs₂Zr₃O_1.5F₅(PO₄)₂ · 2H₂O, Cs₂Zr₃F₂(PO₄)₄ · 4.5H₂O, and Zr₃O₄(PO₄)_1.33 · 6H₂O, which crystallize only in a mixture with known phases. All the compounds were studied by X-ray powder diffraction, crystal-optical, thermal, and IR spectroscopic analyses.     

Thermodynamic study of the zirconium-aluminum system

The heats of formation of the zirconium-aluminum intermetallic compounds ZrAl₃, ZrAl₂, Zr₂Al₃, ZrAl, Zr₅Al₄, Zr₃Al₂, Zr₅Al₃, and the solid solution of aluminum in bcc zirconium have been studied using a Knudsen cell mass spectrometric technique. The high-temperature compound Zr₅Al₄ was identified in the residue of some of these experiments and this led to further heat treatment/X-ray diffraction experiments which indicated that Zr₄Al₃, previously reported to form from the melt, decomposes in the solid state at temperature in excess of 1050°C. By measuring aluminum vapor pressures over the two-phase ranges of the system from 0 < X_Al < 0.75 the enthalpy changes for the decomposition reactions were determined by second- and third-law methods, and these were used along with the measured vapor pressure of aluminum over the solid solution of aluminum in bcc zirconium to derive the enthalpies of formation of the intermetallic phases (in kcal/mole): ZrAl₃, ?38.96; ZrAl₂, ?32.86; Zr₂Al₃, ?56.12; ZrAl, ?21.36; Zr₅Al₄, ?93.76; Zr₃Al₂, ?48.78; Zr₅Al₃, ?74.57.     

Preparation of Ce-Zr-O solid solution

A single phase solid solution of Ce-Zr-O can be made by using NH₄HCO₃ solution as precipitating agent. The influence of preparation conditions, such as pH, Zr⁴⁺/(CO₃ ^2-+HCO₃ ^-) and Ce³⁺/Zr⁴⁺ ratio on the formation of the solid solution were investigated. The results show that a single phase Ce-Zr-O solid solution can be formed only under a narrow window of preparation conditions, indicating that some compounds are formed in the precipitating process. The compound may contain Ce³⁺, Zr⁴⁺, CO₃ ^2-, HCO^3-, and OH^-. The solid solution so prepared can be described as Ce_0.37Zr_0.63O₂. This revised version was published online in August 2006 with corrections to the Cover Date.     

Heavy Chains: Synthesis,Reactivity and Decomposition of Interpnictogen Chains with Terminal Diaryl Bismuth Fragments

In this work, we report the preparation of multiple interpnictogen chain compounds with three consecutive pnictogen atoms and terminal Ar₂Bi fragments (Ar=Ph, Mes). Symmetrical compounds of the form Ar₂Bi−E(tBu)−Bi₂Ar ( 1 : Ar=Ph, E=P; 2 : Ar=Ph, Mes, E=As) as well as ternary interpnictogen compounds of the form Ar₂Bi−E¹(tBu)−E²tBu₂ (Ar=Ph, Mes; 4 : E¹=P, E²=As; 5 : E¹=P, E²=Sb; 6 : E¹=As, E²=P) were prepared. The decomposition in solution at room temperature and under the influence of light was studied for compounds 1 – 6 . The reactivity of 1_Ph and 2_Ph with the small N-heterocyclic carbene 1,3,4,5-tetramethylimidazol-2-ylidene (Me₂IMe) was also studied. In the case of 1_Ph , the formation and consecutive decomposition of Me₂IMe=PtBu ( 8 ) was observed in solution. Hence, it was shown that 1_Ph can react as a “masked phosphinidene”. In the case of 2_Ph , no reaction with Me₂IMe was observed. All isolated compounds were analysed by NMR and IR spectroscopy, mass spectrometry, elemental analysis and single-crystal X-ray diffraction.     

Die Reaktionen von Trithiazylchlorid mit Zirkoniumtetrachlorid Die Kristallstruktur von (S4N4CI)2[Zr2CI10]

Reactions of Zirconium Tetrachloride with Trithiazylchloride. Crystal Structure of (S₄N₄)[Zr₂Cl₁₀] Zirconium tetrachloride reacts with (NSCI)₃ yielding (S₃N₃CI₂)₂[Zr₂CI₁₀], S₄N₄[Zr₂CI₁₀], or (S₄N₄CI)₂[Zr₂CI₁₀], depending of the reaction conditions. These compounds were characterized by their i.r. spectra. They have an ionic structure containing the known ions S₃N₃CI₂⊕, S₄N₄^2⊕, S₄N₄CI^⊕, and the thus far unknown [Zr₂CI₁₀]^2? ion. According to the X-ray structure determination (2827 independent observed reflexions, R = 0.027), (S₄N₄CI)₂[Zr₂CI₁₀] crystallizes in the space group P&1macr; with the lattice constants a = 688, b = 1132, c = 1827 pm, α = 103.2°, β = 98.7° and γ = 91.9⁰ and with Z = 2 formula units per unit cell. The structure is built up from S₄N₄CI^⊕ ions, which are nearly identical as in S₄N₄CI[FeCI₄] and from [Zr₂CI₁₀]^2? ions in which two chloro bridges join two edge-sharing octahedra.     

Phase equilibria in Cu-Al-Zr system at 1073 K and aluminum concentration of less than 55 at %

X-ray diffraction and electron probe microanalysis were used to investigate phase equilibria in the ternary Cu-Al-Zr system at 1073 K in the Zr-rich region. The fragment of the isothermal section of the system was plotted. The regions of homogeneity of the ternary ZrCu₂Al and ZrCu _x Al_{2 ? x} phases were investigated. The type of phase equilibria between binary and ternary compounds of the Al-Cu-Zr system was established. It was found out that, at a Zr concentration above 55 at %, ternary compounds are not formed, and the Zr₃Al and Zr₂Cu phases were in equilibria with ??-Zr at 1073 K.     

Catalytic polymerization of ethylene by non-metallocene Zirconium(IV) calix[4] pyrrole complexes

Some zirconium compounds containing chelating diamido dipyrrole or tetra-amido tetra-pyrrole ligands were synthesized and used as polymerization catalyst with high polymerization activity of ethylene at 40 °C and 1 bar, in presence of MAO or B(C₆F₅)₃ as co-catalyst. The maximum catalytic activity reached 1100 Kg/mol bar h for ethylene polymerization by Zr₂(octa-phenyl calix[4]pyrrolidine)Cl₄. These results reveal that half-zirconocene like complexes including four terminal chlorine and one calix[4]pyrrolidine in middle with both π and σ-interaction have the highest ethylene polymerization turnover (compounds 13, 14).     

Thermal analysis of pigments based on Bi2O3

The synthesis of new pigments based on Bi₂O₃ is investigated because they give interesting orange hues and can substitute the pigments problematic from the environmental point of view. Chemical compounds of the Bi_2–xZr_3x/4O₃ type were synthesized. The host lattice of these pigments is Bi₂O₃ that is doped by Zr⁴⁺ ions. The area of ZrO₂ solubility in Bi₂O₃ at 800°C forming solid solution of both oxides was studied. The incorporation of doped ions provides interesting colours and contributes to a growth of the thermal stability of these compounds. The simultaneous TG-DTA measurements were used for determination of the temperature region of the pigment formation and thermal stability of pigments.     

Thermal analysis of doped Bi<Subscript>2</Subscript>O<Subscript>3</Subscript>

New environmentally inorganic pigments based on Bi₂O₃ doped by metal ions, such as Zr⁴⁺ and Dy³⁺ have been developed and characterized using the methods thermal analysis, X-ray powder diffraction, and spectral reflectance data. The compounds having formula Bi_2−x Dy _x/2Zr_3x/8O₃ (x = 0.2, 0.6, 1.0, and 1.2) were prepared by the solid state reaction. Methods of thermal analysis were used for determination of the temperature region of the pigment formation and thermal stability of compounds. The incorporation of doped ions in Bi₂O₃ changes the color from yellow to orange and also contributes to a growth of their thermal stability. This property gives a direction for coloring ceramic glazes.     

Caulerpenyne-Amine Reacting System as a Model for in vivo Interactions of Ecotoxicologically Relevant Sesquiterpenoids of the mediterranean-adapted tropical green seaweed caulerpa taxifolia

Caulerpenyne ( 1 ), the most abundant of the ecotoxicologically relevant sesquiterpenoids of the Mediterranean-adapted tropical green seaweed Caulerpa taxifolia, was found to react with Et₃N or pyridine in MeOH by initial deprotection of C(1)HO to give oxytoxin 1 ( 2a ), previously isolated from the sacoglossan mollusc Oxynoe olivacea. With BuNH₂, without any precaution to exclude light, 1 gave the series of racemic 3 and 4 , and achiral (4E,6E)- 5 , (4E,6Z)- 5 , (4Z,6E)- 5 , and (4Z,6Z)- 5 pyrrole compounds, corresponding to formal C(4) substitution, 4,5-β-elimination, and (E/Z)-isomerization at the C(4)?C(5) and C(6)?C(7) bonds. Changing to CDCl₃ as solvent in the dark, 1 gave cleanly, via 2a as an intermediate, 3 and (4E,6E)- 5 . The latter proved to be prone to (E/Z)-photoisomerization. Under standard acetylation conditions, 3 gave (4E,6E)- 5 via acetamide 7 as an intermediate. Particular notice is warranted by selective deprotection of 1 at C(1), mimicking enzyme reactions, and unprecedented formation of pyrrole compounds from freely-rotating, protected 1,4-dialdehyde systems.     

New isomeric N‐substituted hydrazones of 2‐, 3‐ and 4‐pyridinecarboxaldehydes and methyl‐3‐pyridylketone

Twelve compounds unknown in the literature N‐(E)‐2‐stilbenyloxymethylenecarbonyl substituted hydrazones of 2‐, 3‐ and 4‐pyridinecarboxaldehydes, as well as methyl‐3‐pyridylketone have been prepared. The stereochemical behavior of these compounds in dimethyl‐d₆ sulfoxide solution has been studied by ¹H NMR technique. The E geometrical isomers and cis/trans amide conformers have been found for N‐substituted hydrazones 1–12. EI induced mass spectral fragmentation of these compounds were also investigated. The data obtained create the basis for distinguishing isomers.     

Selective Formation and Unusual Reactivity of Tetraarsabicyclo[1.1.0]butane Complexes

The selective formation of the dinuclear butterfly complexes [{Cp′′′Fe(CO)₂}₂(μ,η^1:1‐E₄)] (E=P ( 1 a ), As ( 1 b )) and [{Cp*Cr(CO)₃}₂(μ,η^1:1‐E₄)] (E=P ( 2 a ), As ( 2 b )) as new representatives of this rare class of compounds was found by reaction of E₄ with the corresponding dimeric carbonyl complexes. Complexes 1 b and 2 b are the first As₄ butterfly compounds with a bridging coordination mode. Moreover, first studies regarding the reactivity of 1 b and 2 b are presented, revealing the formation of the unprecedented As₈ cuneane complexes [{Cp′′′Fe(CO)₂}₂{Cp′′′Fe(CO)}₂(μ₄,η^1:1:2:2‐As₈)] ( 3 b ) and [{Cp*Cr(CO)₃}₄(μ₄,η^1:1:1:1‐As₈)] ( 4 ). The compounds are fully characterized by NMR and IR spectroscopy as well as by X‐ray structure analysis. In addition, DFT calculations give insight into the transformation pathway from the E₄ butterfly to the corresponding cuneane structural motif.     

The regio- and stereospecific synthesis of diarylpropenyllithium compounds from dimethylamino- and dimethylaminomethyl-substituted diarylacetylenes via transmetallation reactions involving diarylpropenylmagnesium and -tin compounds

Dimethylamino- and dimethylaminomethyl-substituted diarylacetylenes were prepared by the Pd(PPh₃)₄-catalyzed coupling reaction of dimethylamino- and dimethylaminomethyl-substituted aryl halides with arylacetylenes.Reaction of the asymmetric diarylacetylenes with methylmagnesium bromide in the presence of NiCl₂(PPh₃)₂ gave stereo- and regio-selectively cis addition products in which the aryl group bearing the built-in ligand (Me₂N or Me₂NCH₂) and the magnesium atom are bonded to the same unsaturated carbon atom. The E-diarylpropenylmagnesium bromides were converted in two successive transmetallation steps into the corresponding E-triphenyltin and Z-lithium compounds with retention of configuration. Depending on the type of solvent, complete inversion of configuration was observed for the Z-diarylpropenyllithium compounds. From the E-lithium compounds the corresponding Z-diarylpropenyltriphenyltin compounds were prepared (Scheme 1).Retention of configuration in the series of transmetallation reactions has unambiguously been established by comparison of the ¹¹⁹Sn¹H, ¹³C¹H and ¹¹⁹Sn¹³C coupling constants observed in the ¹H and ¹³C NMR spectra of the configurationally pure stereoisomeric pairs.     

Synthesis of zirconium (hafnium) fluoride compounds and their X-ray luminescence properties

Twenty-five zirconium (hafnium) fluoride compounds have been synthesized at room temperature in the systems MO₂-H₂SO₄-M′_nA(HF)-H₂O (M = Zr (Hf); M′ = Na, K, Rb, Cs, NH₄; A = F, SO₄) and their X-ray luminescence spectra (luminescence wavelengths and relative intensities) have been measured. The X-ray luminescence of the compounds has been considered as a function of the composition (cations, anions, water content) and different structural factors (CNs, polyhedra, H-bonds). Ammonium compounds do not luminesce, and sodium fluorozirconates and heptafluorozirconates are weakly luminescing. Hexafluorozirconates M₂Zr(Hf)F₆ (M= K, Rb, Cs) and M₅Zr₄F₂₁ · 3H₂O (M = Rb, Cs), as well as oxofluorozirconate Rb₂Zr₃OF₁₂, are strongly luminescing compounds.     

Reactions of early-late heterobimetallics with oxiranes: New examples for cooperative reactivity

In the reaction of oxiranes and cobalt-containing early-late heterobimetallic (ELHB) compounds isolated or prepared in situ, acyl-cobalt complexes, Y₃M^EOCHRCH₂C(O)Co(CO)₄ (1, M^E = Ti, Zr, Hf), were obtained. Some of the complexes 1 were isolated in form of their derivatives substituted on the cobalt atom with PPh₃. We have demonstrated that the ELHB compounds containing Group 4 metals and silyl-cobalttetracarbonyls are analogous concerning their reactivity against oxiranes. The studied heterobimetallic systems mediated the rearrangement of terminal oxiranes to ketones.