Binary Lead Fluoride Pb3F8

The binary lead fluoride Pb₃F₈ was synthesized by the reaction of anhydrous HF with Pb₃O₄ or by the reaction of BrF₃ with PbF₂. The compound was characterized by single-crystal and powder X-ray diffraction, IR, Raman, and solid-state MAS ¹⁹F NMR spectroscopy, as well as thermogravimetric analysis, XP and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. Solid-state quantum-chemical calculations are provided for the vibrational analyses and band assignments. The electronic band structure offers an inside view of the mixed valence compound.     

Synthesis and study of lead(II) uranate Pb(UO<Subscript>2</Subscript>)<Subscript>2</Subscript>O<Subscript>2</Subscript>(OH)<Subscript>2</Subscript>·H<Subscript>2</Subscript>O

An individual crystalline compound Pb(UO₂)₂O₂(OH)₂·(H₂O) was obtained by reaction of synthetic schoepite UO₃·2.25H₂O with an aqueous solution of lead(II) nitrate under hydrothermal conditions. The composition and structure of this compound were determined, and the processes of its dehydration and thermal decomposition were studied by chemical analysis, X-ray diffraction, IR spectroscopy, and thermography.     

Synthesis,Structure and Thermal Decomposition of the Bismuth Silyltellurolate Bi(TeSitBu2Ph)3

The compound Bi(TeSitBu₂Ph)₃ ( 1 ) was obtained from the reaction of BiCl₃ with tBu₂PhSiTeSiMe₃ in diethyl ether. The single crystal structure analysis revealed a trigonal pyramidal structure of the BiTe₃ core and weak Bi···C_(arene) contacts. Compound 1 was characterized by multinuclear NMR spectroscopy, IR spectroscopy and elemental analysis. Thermogravimetric experiments show that compound 1 decomposes with formation of Bi₂Te₃ or a mixture of elemental bismuth and Bi₄Te₃, depending on the pressure conditions.     

Thermal and Structural Investigation of The Reaction Between 1,2-propanediol and Ni(NO3)2⋅6H2O

The authors present the results of an investigation concerning the reaction between 1,2-propanediol and Ni(NO₃)₂6H₂O, leading to a complex containing as ligand the lactate anion (L), suggesting that the oxidation of 1,2-propanediol occurs at the primary hydroxyl group. The obtained solid homopolynuclear combination, [Ni₂(OH)₂L₂(H₂O)₂0.5H₂O]_n, has been investigated by thermal analysis, electron and IR spectroscopy,and magnetic methods. Nickel oxide obtained by thermolysis of this complex compound was characterized by IR, X-ray spectroscopy and elemental analysis. All the investigations lead to the conclusion that the complex compound is characterized by pseudooctahedral configuration of the nickel(II) ion. Thermal analysis of the homopolynuclear complex compound enabled to prove the thermal decomposition mechanism.This revised version was published online in November 2005 with corrections to the Cover Date.     

Bridging vs. Chelating Coordination Modes of Vinylsilanes in CuI π‐Complexes: Structure and Stability

Two new copper(I) olefin complexes, [Cu₆Cl₆(MTrVS)₂] ( 1 ) and [Cu₂Cl₂(DMVSP)₂] ( 2 ), of tridentate bridging methyltrivinylsilane (MTrVS) and bidentate chelating 2‐[dimethyl(vinyl)silyl]pyridine (DMVSP) have been synthesized and characterized by single‐crystal X‐ray structure analysis, IR and ¹H NMR spectroscopy. It has been shown that using the alkenylsilanes with required electronic properties, molecular symmetry and conformational flexibility, it is possible to control the formation of optimal copper(I) halide oligomers. The obtained results, together with relevant literature data, also illustrate how the coordination mode of vinylsilanes is related to Cu–(C=C) bond strengthening and, consequently, to stability of the organometallic compounds. In particular, we suggest that, together with Cu–C_α distance shortening accompanied by a segmentation of π‐conjugated chelate ring, complex shows an increased lability to form probably an alkenylcopper intermediate in the homocoupling reaction of alkenyl(2‐pyridyl)silanes. At the same time, no appreciable reduction of thermal stability of π‐conjugated chelate complex 2 with respect to bridged compound 1 emerges.     

Thermal studies of potassium tetrahydroborate−sodium tetrafluoroborate mixtures

The KBH₄?NaBF₄ mixture was studied by thermal analysis (differential scanning calorimetry). Chemical analysis, X-ray powder diffraction analysis, IR spectroscopy, and ¹¹B and ¹⁹F MAS NMR spectroscopy showed that the primary stage of the complex pyrolysis process is a metathesis reaction between components to form a new mixture, NaBH₄?KBF₄, the decomposition of which with the release of gaseous products and the formation of polyhedral borohydride compounds (mainly B₁₂H₁₂ ^2-) in the solid residue begins at a temperature of about 563 K. At a certain ratio between reactants in the initial mixture KBH₄?NaBF₄, the B₁₂H₁₂ ^2- anion can form with the material participation of the BF₄ ^- anion.     

Synthesis and properties of isopropylamine borane i-C3H7NH2 · BH3

Isopropylamine borane i-C₃H₇NH₂ · BH₃ was synthesized by the reaction of sodium tetrahydroborate NaBH₄ with isopropylamine hydrochloride in tetrahydrofuran followed by extraction with diethyl ether. Its synthesis conditions were determined and optimized. The compound was characterized by chemical analysis, IR spectroscopy, and differential thermal analysis.     

Phase transitions of intercalation inclusion compounds C2F0.92Br0.0·yCH3CN in the temperature range 20–260°C

X-ray phase analysis (XRPA), differential thermal analysis (DTA), and IR spectroscopy studies were performed to investigate stepwise transitions of the fluorographite intercalation inclusion compound (host) with acetonitrile (guest). When heated in a guest atmosphere to 260(±8)°C, the compound of the first stage of saturation with a spacing of I _c = 9.47 Å undergoes sequential disproportionation into gaseous acetonitrile, a compound of the second stage (I _c = 15.52 Å), a compound of the fourth stage of occupation (I _c = 27.77 Å), and solid solutions based on the fluorographite matrix (I _c = 6.05 Å) that form “residual compounds.” In air the “residual compound” of graphite fluoride is formed at lower temperatures. Conditions of mutual transitions and formation of metastable states have been determined for which the domain model with coexisting microphases of different stages of occupation is discussed.     

Reactions of zirconium tetrachloride with pivalic acid in organic solvents under heating

Reactions of zirconium tetrachloride with pivalic acid in benzene, toluene, m- and o-xylene, and in excess pivalic acid at the boiling temperature of a solvent were studied. The product of reactions in aromatic solvents was found to have the composition corresponding to the formula Zr₂O(Piv)₆. The reaction in excess pivalic acid resulted in the formation of the compound Zr(Piv)₄. The reaction products were investigated by X-ray powder diffraction, IR and NMR spectroscopy, and their physicochemical properties were compared with those of zirconium tetrapivalate synthesized by a mechanically activated solid-phase reaction between ZrCl₄ and sodium pivalate.     

(NH 4 )Zn 2 (PO 4 )(HPO 4 ): Hydrothermal Synthesis and Reaction with n-Alkylamine Vapours

(NH₄)Zn₂(PO₄)(HPO₄) was synthesized under mild hydrothermal conditions in the presence of urea. The reaction with n-alkylamines has been investigated by exposing the solid to amines vapor. The new materials were characterized by chemical and thermal analysis, powder X-ray diffraction, and IR spectroscopy. In addition, the simultaneous reaction of this compound with two or more n-alkylamine different molecules was investigated. The reaction of large n-alkylamine molecules was observed to be faster if there is a shorter alkyl chain amine acting as a catalyst, yielding on completion single amine materials. In the case of a vapor mixture of several amines, the compound obtained depends on the reaction time.     

Disodium[hydroxotetranitronitrosyl]ruthenate(II), a Photochromic Substance with Long‐lived Metastable States: Structure at 110 K,Spectroscopic and Thermal Properties

Disodium[hydroxotetranitronitrosyl]ruthenate(II) is a photochromic compound excitable with blue‐green light which exhibits at least one unusually long‐lived metastable state at low temperature. At 298 K, the compound crystallises in the space group C2/m. A reversible phase transition occurs at 240 K upon cooling, as detected by Differential Scanning Calorimetry and X‐ray powder diffraction which causes a lowering of the crystal symmetry to the space group P2₁/n. Synchrotron X‐ray single crystal diffraction and FT‐IR spectroscopy data obtained on the ground and the excited states of the title compound low temperature phase are presented.     

Reaction of niobium pentoxide with ammonium hydrodifluoride

The reaction between Nb₂O₅ and NH₄HF₂ is studied by thermogravimetric analysis, IR spectroscopy, and crystal-optical analysis. Intermediates and their formation temperatures are determined.     

Kinetics and Mechanism of Acetylene Reduction with Europium Amalgam Catalyzed by Isolated Active Center of Nitrogenase

The reaction kinetics of C₂H₂ reduction with europium amalgam (Eu/Hg) catalyzed by nitrogenase active center separated from the enzyme, the molybdenum–iron–sulfur cluster [MoFe₇S₉ · homocitrate] (FeMoco), was studied. The dependence of the rates of ethylene and ethane formation on the concentrations of catalyst, substrate, protonating agent, and amalgam was studied. The stereospecificity of the reaction was studied by Fourier transform IR spectroscopy. It was found that the reaction occurred at the amalgam surface via the adsorption of the compound [FeMoco · PhSH]. Upon reduction, this compound can simultaneously coordinate several substrate molecules to activate them for the subsequent reactions. A study of the IR spectra of the gas phase of the reaction demonstrated that cis-1,2-dideuterioethylene is the main product of C₂D₂ reduction. Taking into account this fact and the dependence of the reaction rate on the concentration of a protonating agent, we concluded that substrate molecules bound to the cofactor underwent protonation by intramolecular hydrogen transfer from the iron or sulfur atoms of FeMoco to coordinated C₂H₂.     

Synthesis,Structure, and Physicochemical Properties of Lithium Uranovanadate

A new chemical compound, lithium uranovanadate, was synthesized and studied by X-ray diffraction, IR spectroscopy, and thermography. Standard enthalpies of formation of lithium uranovanadate and its dihydrate at 298.15 K were determined by means of reaction and adiabatic vacuum calorimetry. Temperature dependence of heat capacity in the range 80-300 K was obtained for crystalline LiVUO₆·2H₂O and thermodynamic characteristics of its synthesis were calculated.     

Functional model of oxomolybdoenzymes: Synthesis and characterization of a molybdenum complex with sulphur and pterin ligands exhibiting saturation kinetics with pyridine N-oxide

Redox reaction between 6-acetonylisoxanthopterin (H₂pte) and [Mo^VIO₂ (ssp)] [ssp = anion of 2-(salicylideneamino) benzenethiol] in CH₃OH-C₂H₅OH medium produces a new mixed ligand compound [Mo^IV (ssp) (Hpte) (OCH₃)] (1). It has been characterized by elemental analysis, ESMS data, UV-Vis, IR,¹HNMR (1D and 2D) spectroscopy and cyclic voltammetry. Kinetics of formation of this compound as well as that of its reaction with pyridine N-oxide have been followed spectrophotometrically. Both the reactions follow substrate saturation kinetics and involve metal-centred oxygen atom transfer process. Large negative values of entropy of activation indicate the operation of associative mechanism.     

Coordination chemistry of the ligand 7-aza-1-hydroxy-benzotriazole. Crystal structures and antimicrobial activity of the catena-poly-[μ-chlorido(μ-7-aza-1-oxy-κN:O-benzotriazolyl-κN)]cobalt(II)methanol coordination polymer and of a new polymorph of the free ligand 3H-[1,2,3]triazolo[4,5-b]pyridin-3-ol

Reaction of cobalt chloride and 7-aza-1-hydroxy-benzotriazole (HOazbt) in alcoholic solution results in formation of the polymeric compound [Co(C₅H₃N₄O)(CH₃OH)Cl]_n. The compound has been characterized by elemental analysis, IR spectroscopy, and its 3D structure was determined by X-ray diffraction. Also its antimicrobial activity was determined.     

Synthesis and spectral characteristics of the combined ligand copper complex with proline and corazole

Synthesis of the combined ligand complex of copper(II) prolinate bis(1,5-pentamethylenetetrazole) [Cu(PMT)₂](Pro)₂ was carried out. The product is interesting as a biologically active compound. It is obtained by reaction of copper carbonate with proline followed by further reaction with corazole. The composition and structure of the complex were confirmed by elemental analysis and data of UV, IR, and ¹H NMR spectroscopy. The complex was characterized in detail by the method of circular optical dichroism.     

Interaction of nitrogen dioxide with sublimed films ofmeso-tetraphenylporphyrinatozinc

The interaction of NO₂ with sublimed films ofmeso-tetraphenylporphyrinatozinc was studied by IR and UV-VIS spectroscopy. The π-radical cation (ZnTPP)^•+NO₂ ⁻ containing an unpaired electron on HOMO of the A_2u symmetry is formed at the first stage of the reaction. The second NO₂ molecule attacks themeso-carbon atom to form zinc isoporphyrin with the covalently bound nitro group. The IR data indicate that the NO₂ ⁻ anion is axially coordinated to the central metal atom, and the NO₂ group is covalently bonded through the N atom. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 665–668, April, 1998.     

Synthesis and study of sodium triuranate Na<Subscript>2</Subscript>(UO<Subscript>2</Subscript>)<Subscript>3</Subscript>O<Subscript>3</Subscript>(OH)<Subscript>2</Subscript>

Sodium triuranate Na₂(UO₂)₃O₃(OH)₂ was synthesized by the reaction between aqueous uranyl acetate solution and aqueous sodium nitrate solution under hydrothermal conditions at 200°C. The composition and structure of the synthesized compound were determined, and its dehydration and thermal decomposition were studied, by chemical analysis, X-ray diffraction, IR spectroscopy, and thermal analysis.     

New acenaphthene-1,2-diimine and its reduction to the tetraanion. Molecular structures of 1,2-bis[(trimethylsilyl)imino]acenaphthene and its lithium derivatives

1,2-Bis[(trimethylsilyl)imino]acenaphthene (1) was synthesized by the reaction of acenaphthenequinone with (Me₃Si)₂NLi in toluene followed by treatment of the reaction product with trimethylchlorosilane. The dianionic derivative [(tms-BIAN)Li₂]₂ (3) was obtained as the final product by reduction of compound 1 with lithium in toluene, whereas reduction in diethyl ether afforded the tetraanion [(tms-BIAN)Li₄(Et₂O)₃]₂ (5). The formation of the paramagnetic mono-and trianions in solution was confirmed by ESR spectroscopy. Compounds 3 and 5 were isolated in the crystalline state and characterized by elemental analysis, IR spectroscopy, and NMR spectroscopy. The crystal structures of 1, 3, and 5 were established by X-ray diffraction. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 697–705, April, 2006.