Thermal properties,phase transitions,vibrational and reorientational dynamics of [Mn(NH<Subscript>3</Subscript>)<Subscript>6</Subscript>](NO<Subscript>3</Subscript>)<Subscript>2</Subscript>

[Mn(NH₃)₆](NO₃)₂ crystallizes in the cubic, fluorite (C1) type crystal lattice structure (Fm \( \overline{3} \) m) with a = 11.0056 Å and Z = 4. Two phase transitions of the first-order type were detected. The first registered on DSC curves as a large anomaly at T _C1 ^h  = 207.8 K and T _C1 ^c  = 207.2 K, and the second registered as a smaller anomaly at T _C2 ^h  = 184.4 K and T _C2 ^c  = 160.8 K (where the upper indexes h and c denote heating and cooling of the sample, respectively). The temperature dependence of the full width at half maximum of the band associated with the δ_s(HNH)F_1u mode suggests that the NH₃ ligands in the high temperature and intermediate phase reorientate quickly with correlation times in the order of several picoseconds and with activation energy of 9.9 kJ mol^?1. In the phase transition at T _C2 ^c probably only a some of the NH₃ ligands stop their reorientation, while the remainders continue to reorientate quickly with activation energy of 7.7 kJ mol^?1. Thermal decomposition of the investigated compound starts at 305 K and continues up to 525 K in four main stages (I–IV). In stage I, ²/₆ of all NH₃ ligands were seceded. Stages II and III are connected with an abruption of the next ²/₆ and ¹/₆ of total NH₃, respectively, and [Mn(NH₃)](NO₃)₂ is formed. The last molecule of NH₃ per formula unit is freed at stage IV together with the simultaneous thermal decomposition of the resulting Mn(NO₃)₂ leading to the formation of gaseous products (O₂, H₂O, N₂ and nitrogen oxides) and solid MnO₂.     

Thermal behaviour of [Mg(DMSO)<Subscript>6</Subscript>](NO<Subscript>3</Subscript>)<Subscript>2</Subscript>

Polymorphism and thermal decomposition of [Mg(DMSO)₆](NO₃)₂, where DMSO =(CH₃)₂SO, were studied by differential scanning calorimetry (DSC) and thermogravimetry (TG). The gaseous products of the decomposition were on-line identified by a quadruple mass spectrometer (QMS). Three phase transitions have been detected for this compound in the temperature range of 95–370 K between the following solid phases: stable KIb↔stable KIa at T _C3=195 K, metastable KII↔supercooled K0 at T _C2=230 K and stable KIa→stable K0 at T _C1=337 K. Thermal decomposition of the title compound proceeds in three main stages. In the first stage, which starts just above ca. 380 K, and is continued up to ca. 540 K, the compound loses in two steps four DMSO molecules per one formula unit and undergoes into [Mg(DMSO)₂](NO₃)₂. The second stage starts just immediately after liberating four DMSO ligands and is connected with the decomposition of [Mg(DMSO)₂](NO₃)₂ and the formation of a mixture of solid anhydrous magnesium sulfate, magnesium nitrate and magnesium oxide and also a mixture of gaseous products of the DMSO and Mg(NO₃)₂ decomposition. The third and the last stage corresponds to the decomposition of not decomposed yet magnesium nitrate and formation of magnesium oxide, nitrogen oxides and oxygen.     

Crystal structure of bis(semicarbazido)copper(II) nitrate [Cu(NH<Subscript>2</Subscript>NHC(O)NH<Subscript>2</Subscript>)<Subscript>2</Subscript>](NO<Subscript>3</Subscript>)<Subscript>2</Subscript>

The crystal structure of bis(semicarbazido)copper(II) nitrate [Cu(NH₂NHC(O)NH₂)₂](NO₃)₂ has been studied by X-ray diffraction. Monoclinic crystals, a = 6.835(2) Å, b = 7.733(2) Å, c = 10.320(3) Å, β = 105.701(3)°, V = 525.1(2) ų, space group P2₁/c, Z = 2, d _msd = 2.136 g/cm³, μ(MoK _α) = 2.143 mm⁻¹. The structure was solved with the program for automatic analysis of Patterson’s function and refined by full-matrix least squares in an anisotropic approximation for all non-hydrogen atoms using 753 independent reflections; R ₁ = 0.0203. The square environment of the Cu atom is formed from the amino nitrogen atoms of the hydrazine fragments and the C=O oxygen atoms of the two semicarbazide bidentate molecules (Cu-N 1.928 Å, Cu-O 1.999 Å). The axial positions are occupied by the O atoms of the NO ₃ ⁻ outer-spheric anions (Cu-O 2.505 Å). In the structure, the complex cations and the NO ₃ ⁻ anions are linked into a framework by N-H...O type hydrogen bonds. Original Russian Text Copyright ? 2007 by G. V. Romanenko, Z. A. Savelieva, and S. V. Larionov __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 48, No. 2, pp. 370–373, March–April, 2007.     

Thermal behaviour of [Ca(H<Subscript>2</Subscript>O)<Subscript>4</Subscript>](NO<Subscript>3</Subscript>)<Subscript>2</Subscript>

Motor gasoline must present characteristics that guarantee its quality and the good performance of internal combustion engines without harming the environment. The contamination of gasoline by solvents can seriously adulterate its physical-chemical properties and affect its volatility and detonation capacity. To investigate organic solvent adulteration in gasoline samples, thermal analysis technique (TG/DTG) can be used as an auxiliary tool in the study of the thermal behavior of liquid fuels, as demonstrated by the present work involving a comparative analysis of kerosene-free and doped gasoline.     

Synthesis,structure and thermal decomposition of [Ni(NH<Subscript>3</Subscript>)<Subscript>6</Subscript>][VO(O<Subscript>2</Subscript>)<Subscript>2</Subscript>(NH<Subscript>3</Subscript>)]<Subscript>2</Subscript>

The compound [Ni(NH₃)₆][VO(O₂)₂(NH₃)]₂ was prepared and characterized by elemental analysis and vibrational spectra. The single crystal X-ray study revealed that the structure consists of [Ni(NH₃)₆]²⁺ and [VO(O₂)₂(NH₃)]⁻ ions. As a result of weak interionic interactions V′···O_p (O_p-peroxo oxygen), ([VO(O₂)₂(NH₃)]⁻)₂ dimers are formed in the solid-state. The thermal decomposition of [Ni(NH₃)₆][VO(O₂)₂(NH₃)]₂ is a multi-step process with overlapped individual steps; no defined intermediates were obtained. The final solid products of thermal decomposition up to 600°C were Ni₂V₂O₇ and V₂O₅.     

[Zn(NH<Subscript>3</Subscript>)<Subscript>4</Subscript>][PtCl<Subscript>6</Subscript>] and [Cd(NH<Subscript>3</Subscript>)<Subscript>4</Subscript>][PtCl<Subscript>6</Subscript>] as precursors for intermetallic compounds PtZn and PtCd

Double complex salts (tetraamminezinc and tetraamminecadmium hexachloroplatinates) have been synthesized. Their thermal properties have been studied, as well as the products of their degradation in hydrogen and helium atmospheres. Optimal thermolysis schedules have been determined. Thermolysis under hydrogen yields intermetallic compounds PtZn and PtCd.     

[Co(NH<Subscript>3</Subscript>)<Subscript>6</Subscript>](WO<Subscript>4</Subscript>)Cl: Synthesis,crystal structure,and thermal properties

The crystal structure of [Co(NH₃)₆](WO₄)Cl complex salt is determined by single crystal X-ray. The thermal properties are examined, and the products obtained on heating the salt in different gaseous atmospheres are analyzed by powder X-ray diffraction.     

Supramolecular 2D structure of [Co(2-Me-Pyz)<Subscript>2</Subscript>(H<Subscript>2</Subscript>O)<Subscript>4</Subscript>](NO<Subscript>3</Subscript>)<Subscript>2</Subscript>

The complex [Co(2-Me-Pyz)₂(H₂O)₄](NO₃)₂ is synthesized and its structure is determined. The crystals are monoclinic: space group P2₁/n, a = 10.685(2) Å, b = 6.837(1), c = 12.515(3) Å, β = 91.84(3)°, V = 913.8(3) ų, ρ_calcd = 1.042 g/cm ³, Z = 2. The Co²⁺ ion (in the inversion center) is coordinated at the vertices of the distorted octahedron by two nitrogen atoms of methylpyrazine and four oxygen atoms of the water molecules (Co(1)–N(1) 2.180(3), average Co(1)–O(w) 2.079(3) Å, angles at the Co atom 87.9(1)–92.1(1)°). Supramolecular pseudometallocycles are formed in the structure through the O(w)–H…N(1) hydrogen bonds between the coordinated H₂O molecules and the terminal nitrogen atoms of the 2-methylpyrazine molecules. Their interaction results in the formation of supramolecular layers joined by the NO₃ groups into a three-dimensional framework.     

Crystal structure and properties of [M(NH<Subscript>3</Subscript>)<Subscript>5</Subscript>Cl](NO<Subscript>3</Subscript>)<Subscript>2</Subscript>, (M = Ir,Rh, Ru)

The crystal structures of compounds from the series [M(NH₃)₅Cl](NO₃)₂, (M = Ir, Rh, Ru) were described. The compounds crystallized in the tetragonal crystal system, space group I4, Z = 2. Crystal data for [Ir(NH₃)₅Cl](NO₃)₂ (I): a = 7.6061(1) Å, b = 7.6061(1) Å, c = 10.4039(2) Å, V = 601.894(16) ų, ρ_calc = 2.410 g/cm³, R = 0.0087; [Rh(NH₃)₅Cl](NO₃)₂ (II): a = 7.5858(5) Å, b = 7.5858(5) Å, c = 10.41357(7) Å, V = 599.24(7) ų, ρ_calc = 1.926 g/cm³, R = 0.0255; [Ru(NH₃)₅Cl](NO₃)₂ (III): a = 7.5811(6) Å, b = 7.5811(6) Å, c = 10.5352(14) Å, V = 605.49(11) ų, ρ_calc = 1.896 g/cm³, R = 0.0266. The compounds were defined by IR spectroscopy and XRPA and thermal analyses.     

Thermal decomposition studies of [Ni(NH<Subscript>3</Subscript>)<Subscript>6</Subscript>]X<Subscript>2</Subscript> (X = Cl,Br) in the solid state using TG-MS and TR-XRD

Detailed investigation on the thermal behaviour of hexaamminenickel(II) chloride and hexaamminenickel(II) bromide has been carried out by means of simultaneous TG/DTA coupled online with mass spectroscopy (TG-MS) and temperature-resolved X-ray diffraction (TR-XRD). Evolved gas analyses by TG-MS revealed the presence of NH₂, NH, N₂ and H₂ fragments in addition to ammonia during the deamination process. These transient species resulted due to the fragmentation of the evolved ammonia during pyrolysis. The intermediates formed during the thermal deamination stages were monitored by in situ TR-XRD. The final product of the decomposition was found to be nano size metallic nickel in both cases. Morphology of the complexes, intermediates and the residue formed at various decomposition stages was analysed by scanning electron microscope (SEM). Kinetic analyses using isoconversional method for deamination and dehalogenation reaction show that the activation energies vary with the extent of conversion, indicating the multi-step nature of these solid state decomposition reactions.     

X-ray diffraction study of the monoclinic modification of [Cu(NH<Subscript>3</Subscript>)<Subscript>4</Subscript>](ReO<Subscript>4</Subscript>)<Subscript>2</Subscript> in the range 100-410 K

The monoclinic modification of [Cu(NH₃)₄](ReO₄)₂ complex salt in the range 100-410 K is studied by single crystal X-ray diffraction. The crystallographic data for 300 K are as follows: a = 10.6123(3) Å, b = 7.5443(2) Å, c = 15.2261(4) Å, β = 108.406(1)°, V = 1156.67(5) ų, space group Р2₁/n, Z = 4, d_x = 3.623 g/cm³. The coordination environment of the Cu atom, being a distorted square formed by four nitrogen atoms with Cu–N of 1.997-2.018 Å, is completed by the contacts with two oxygen atoms Cu…O of 2.472 Å and 2.598 Å. The comparative crystal chemical analysis with the triclinic modification of [Cu(NH₃)₄](ReO₄)₂ known in the literature is performed.     

Orientational disorder in crystal structures of (NH<Subscript>4</Subscript>)<Subscript>3</Subscript>ZrF<Subscript>7</Subscript> and (NH<Subscript>4</Subscript>)<Subscript>3</Subscript>NbOF<Subscript>6</Subscript>

Crystal structures of (NH₄)₃ZrF₇ (I) and (NH₄)₃NbOF₆ (II) are refined by X-ray diffraction at room temperature. The compounds are isostructural and belong to the structural type of elpasolite: space group F23; a(I) = 9.4185(3) Å, a(II) = 9.3371(5) Å; V(I) = 835.50(5) ų, V(II) = 814.02(8) ų; Z = 4; R(I) = 0.0145, and R(II) = 0.0138. The refinement of the structures in the space group Fm3m yields abnormally short X-X distances in the pentagonal bipyramid MX₇ (X = F, O). The oxygen atom in II is identified by Nb-X distances and occupies one of the axial vertices of the bipyramid. The Nb atom in II is statistically distributed over the position 24f, while Zr in I resides in the symmetry center. The pentagonal bipyramid MX₇ has six independent orientations in I and twelve in II. One of three crystallographically independent ammonium groups of the structures is disordered over six or twelve equivalent orientations.     

Thermolysis of [Pt(NH<Subscript>3</Subscript>)<Subscript>4</Subscript>][ReHlg<Subscript>6</Subscript>] (Hlg = Cl,Br). Structure refinement for [Pt(NH<Subscript>3</Subscript>)<Subscript>4</Subscript>][ReCl<Subscript>6</Subscript>]

Thermal decomposition of [Pt(NH₃)₄][ReHlg₆] binary complex salts (Hlg = Cl, Br) in a hydrogen atmosphere has been studied. Polycrystal X-ray diffractometry indicated that two-phase metallic systems are the final products of thermolysis. Structure refinement was performed for [Pt(NH₃)₄][ReCl₆] by the combined technique involving decomposition of the diffractogram into individual reflections, isolation of reflections most sensitive to the position of separate light atoms, and full-profile analysis. Crystal data for PtReN₄Cl₆H₁₂: a = 11.616(1) Å, b = 10.998(1) Å, c = 10.377(1) Å, V = 1148.1 ų, space group Cmca, Z = 4, d _x = 3.831 g/cm³. The indices are R_p = 5.48%, R_wp = 10.01%, R(F²) = 12.62%. The coordination polyhedron of Re is an almost regular octahedron: Re-Cl 2.34–2.36 Å, ∠ Cl-Re-Cl 86.9–90.3°; the coordination polyhedron of Pt is a square: Pt-N 2.04 Å, ∠N-Pt-N 90.4°.     

Oxonitrates VO(NO<Subscript>3</Subscript>)<Subscript>3</Subscript> and MoO<Subscript>2</Subscript>(NO<Subscript>3</Subscript>)<Subscript>2</Subscript> and nitronium and nitrosonium nitratometallates as nitrating agents

Dissolution of vanadium in anhydrous HNO₃ followed by exposure of the solution in a dessicator over P₂O₅ gave liquid vanadyl trinitrate (I). The X-ray diffraction analysis of I was carried out for a single crystal grown on cooling the liquid in a sealed capillary. The structure is composed of VO(NO)₃ molecules in which the V atom has an unusually high C.N. 7; it coordinates the terminal O atom and three bidentate nitrate groups to form a distorted pentagonal bipyramid as the coordination polyhedron with the terminal O atom occupying one axial vertex. Using the GAMESS program package, ab initio calculation of the structure of VO (NO₃)₃ in the liquid phase was carried out. It was shown that in all three physical states, vanadyl trinitrate retains its molecular structure almost invariable. Toluene and naphthalene nitration using I and (NO₂)[Fe(NO₃)₄], NO[Cu(NO₃)₃], (NO)_3/4(NO₂)_1/4[Zr(NO₃)₅], and MoO₂(NO₃)₂ proceeds at high rates at low temperatures to give an unusually high para-nitrotoluene percentage in the products as compared with the ortho-isomer. The activity of the studied compounds in the nitration of naphthalene decreases in the series VO(NO₃)₃ > (NO)_3/4(NO₂)_1/4[Zr(NO₃)₅] > MoO₂(NO₃)₂.     

Structural investigation of [Au(en)<Subscript>2</Subscript>]Cl(ReO<Subscript>4</Subscript>)<Subscript>2</Subscript> and [Au(en)<Subscript>2</Subscript>](ReO<Subscript>4</Subscript>)<Subscript>3</Subscript> complexes

Novel complex salts [Au(en)₂]Cl(ReO₄)₂ (I) and [Au(en)₂](ReO₄)₃ (II), en = ethylenediamine, are obtained. Their crystal structures are determined by single crystal X-ray diffraction. Complex I crystallizes in the triclinic crystal system: a = 6.2172(7) Å, b = 7.1644(8) Å, c = 8.8829(8) Å, α = 96.605(4)°, β = 110.000(4)°, γ = 97.802(4)°, P-1 space group, Z = 1, d _x = 3.905 g/cm³; complex II crystallizes in the monoclinic crystal system: a = 15.244(2) Å, b = 7.6809(8) Å, c = 9.3476(12) Å, β = 127.004(3)°, C2 space group, Z = 4, d _x = 4.057 g/cm³.     

Synthesis and X-ray investigation of Rb<Subscript>2</Subscript>[Pd(NO<Subscript>3</Subscript>)<Subscript>4</Subscript>] and Cs<Subscript>2</Subscript>[Pd(NO<Subscript>3</Subscript>)<Subscript>4</Subscript>]

Powder and single crystal X-ray diffraction studies have been performed for anhydrous nitrate complexes Rb₂[Pd(NO₃)₄] (I) and Cs₂[Pd(NO₃)₄] (II). Crystal data for I: a = 7.843(1) Å, b = 7.970(1) Å, c = 9.725(1) Å; β = 100.39(1)°, V = 597.9(1) Å ³, space group P2₁/c, Z = 2, d _calc = 2.918 g/cm³; for II: a = 10.309(2) Å, b = 10.426(2) Å, c = 11.839(2) Å; β = 108.17(3)°, V = 1209.0(4) ų, space group P2₁/c, Z = 4, d ^calc = 3.408 g/cm³. The structures are formed by isolated [Pd(NO₃)₄]^2? complex anions and alkali metal cations. The plane-square environment of the Pd atom is formed from the oxygen atoms of the monodentate nitrate groups. The geometrical characteristics of the complex anions are analyzed. Compound II has a short contact Pd...Cs 3.252 Å.     

Crystal and molecular structure of ammonium trinitratouranylate NH<Subscript>4</Subscript>[UO<Subscript>2</Subscript>(NO<Subscript>3</Subscript>)<Subscript>3</Subscript>]

Ammonium trinitratouranylate NH₄[UO₂(NO₃)₃] (I) single crystals have been synthesized by the reaction of aqueous solutions of diaquadinitratouranyl tetrahydrate and ammonium nitrate in the presence of nitric acid. The structure of the complex has been studied by X-ray diffraction analysis: space group \(R\bar 3c\), a = 9.361(2), c = 18.883(4) Å; V = 1433.0(5) ų, and Z = 6. The structural units of the NH₄[UO₂(NO₃)₃] crystal—NH ₄ ⁺ cations and [UO₂(NO₃)₃]^? complex anions with three bidentate cyclic nitrato groups—are on crystallographic axes \(\bar 3\). A complex three-dimensional packing arranged by the electrostatic attraction forces between counterions and the N-H...O hydrogen bonds between ammonium cations and trinitratouranylate anions is realized in the structure. X-ray diffraction analysis results are confirmed by IR spectra of NH₄[UO₂(NO₃)₃].     

Phase equilibria in the liquid ternary system [Th(NO<Subscript>3</Subscript>)<Subscript>4</Subscript>(TBP)<Subscript>2</Subscript>]-[Gd(NO<Subscript>3</Subscript>)<Subscript>3</Subscript>(TBP)<Subscript>3</Subscript>]-TBP-isooctane at different temperatures

The phase diagrams of the ternary system [Th(NO₃)₄(TBP)₂]-[Gd(NO₃)₃(TBP)₃]-TBP-isooctane in the temperature range 298.15–333.15 K were constructed.     

Complex salts with participation of [Rh(NH<Subscript>3</Subscript>)<Subscript>6</Subscript>]<Superscript>3+</Superscript> cations

Four complex salts with the polyatomic [Rh(NH₃)₆]³⁺ cation are synthesized and studied by X-ray diffraction. The crystallographic characteristics of [Rh(NH₃)₆](WO₄)Cl are determined and the structures of [Rh(NH₃)₆]Cl₃, [Rh(NH₃)₆](ReO₄)₃·2H₂O, and [Rh(NH₃)₆](MoO₄)Cl·3H₂O are solved. The features of mutual packing of the fragments are studied.     

Phase formation in the LiCl-LiNO<Subscript>3</Subscript>-KCl-Sr(NO<Subscript>3</Subscript>)<Subscript>2</Subscript> system

The LiCl-LiNO₃-KCl-Sr(NO₃)₂ four-component system was studied for the first time by a complex of physicochemical analysis methods, including differential thermal analysis, X-ray diffraction, visual-polythermal, and projection thermographic methods. Eutectic and peritectic invariant point characteristics were determined, and the phase diagram of the system was constructed.