Phase transition and dynamics of NH3 ligands in [Zn(NH3)4](ReO4)2

One phase transition in [Zn(NH₃)₄](ReO₄)₂ at T_c = 393.5 K (on heating) and 392.0 K (on cooling) was found. Thermal stability of this compound was investigated by thermal analysis methods. It decomposes in three main stages. The first two are connected with deamination process, whereas Re₂O₇ evaporates in the last step. The activation energy for NH₃ loss processes was determined from thermogravimetric (TG) measurements. The vibrational and reorientational dynamics of NH₃ ligands in the low-temperature phase was probed by various complementary techniques. It was found that at temperatures close to 150 K, NH⋯O hydrogen bond is formed. Temperature-dependent band shape analysis of properly chosen infrared (IR) band was performed, whose results showed that activation energy for NH₃ reorientational motion (<300 K) is rather small and is approximately equal to 2 kJ mol⁻¹. Neutron and X-ray powder diffraction patterns did not reveal any drastic change in the crystal structure in a wide temperature range.     

Synthesis of [M(NH3)5Cl](ReO4)2 (M = Cr, Co, Ru, Rh, Ir) and investigation of thermolysis products. Crystal structure of [Rh(NH3)5Cl](ReO4)2

Complex salts [M(NH₃)₅Cl](ReO₄)₂, where M = Cr, Co, Ru, Rh, Ir, have been prepared. The crystal structure of [Rh(NH₃)₅Cl](ReO₄)₂ was determined by single crystal X-ray diffraction. Crystal data: a = 17.369(4) Å, b = 7.7990(16) Å, c = 11.218(2) Å, V = 1430.5(5) ų, space group C2/m, Z = 4, d _calc = 3.19 g/cm³, R = 0.0447. Complex salts from the above series are shown to be isostructural; they were defined by X-ray crystallography. Thermal decomposition of the compounds in an inert atmosphere and under hydrogen has been studied. According to X-ray phase analysis (XRPA) data, the M_0.33Re_0.67 (M = Co, Ru, Rh, Ir) monophase solid solutions are the products of reduction of the salts under hydrogen.     

two crystalline modifications of [Au(dien)Cl](ReO4)2: synthesis, structure, and thermal properties

Two crystalline modifications of a new [Au(dien)Cl](ReO₄)₂ complex are studied. The geometric characteristics of the [Au(dien)Cl]²⁺ complex cations are compared, and the way of additional coordination of gold atomos is considered. The thermal properties of the compound are studied in the inert and reducing atmospheres, and for the first time the possibility of the formation of Au_0.1Re_0.9 solid solution based on the hcp lattice of Re is shown.     

Metal solid solutions obtained by thermolysis of Pt and Re salts. Crystal structure of [Pt(NH3)4](ReO4)2

A complex salt of tetraammineplatinum(II) perrhenate [Pt(NH₃)₄](ReO₄)₂ has been synthesized. Crystal data: a = 5.1847(6) Å, b = 7.7397(8) Å, c = 7.9540(9) Å, α = 69.531(3)°, β = 79.656(3)°, γ = 77.649(3)°, V = 290,19(6) ų, space group $P\bar 1$ , Z = 1, d _x = 4.370 g/cm³. The products of decomposition of [Pt(NH₃)₄](ReO₄)₂ in a hydrogen atmosphere were investigated using X-ray phase analysis. In definite temperature modes, these are Pt_0.33Re_0.67 solid solutions based on Re with hcp cell parameters a = 2.76 Å, c = 4.42 Å. The products of thermolysis obtained from other precursor complex salts containing both Pt and Re were investigated. Thus Pt_0.75Re_0.25 solid solution with a = 3.905(3) Å was obtained from (NH₄)₂[ReCl₆]_0.25[PtCl₆]_0.75.     

Bildung von NH4[Hg3(NH)2](NO3)3 und Umwandlung in [Hg2N](NO3)

Formation of NH₄[Hg₃(NH)₂](NO₃)₃ and Transformation to [Hg₂N](NO₃) NH₄[Hg₃(NH)₂](NO₃)₃ ( 1 ) and [Hg₂N](NO₃) ( 2 ) are obtained from conc. aqueous ammonia solutions of Hg(NO₃)₂ at ambient temperature and under hydrothermal conditions at 180 °C, respectively, as colourless and dark yellow to light brown single crystals. The crystal structures {NH₄[Hg₃(NH)₂](NO₃)₃: cubic, P4₁32, a = 1030.4(2) pm, Z = 4, R_all = 0.028; [Hg₂N](NO₃): tetra gonal, P4₃2₁2, a = 1540.4(1), c = 909.8(1) pm, Z = 4, R_all = 0.054} have been determined from single crystal data. Both exhibit network type structures in which [HNHg₃] and [NHg₄] tetrahedra of the partial structures of 1 and 2 are connected via three and four vertices, respectively. 1 transforms at about 270 °C in a straightforward reaction to 2 whereby the decomposition products of NH₄NO₃ are set free. 2 decomposes at about 380 °C forming yellow HgO. Most certainly, 1 is identical with a mineral previously analyzed as “Hg(NH₂)(NO₃)” with the same Hg:N:O ratio.     

Thermal properties of polycrystalline [Mn(NH3)6](ClO4)2

A flavor precursor α-ionyl-β-d-glucoside (IG) was synthesized by Koenigs–Knorr method, and its structure was characterized by proton nuclear magnetic resonance spectroscopy, Fourier transform-infrared spectroscopy, and electro spray ionization mass spectroscopy (MS). Thermal degradation behaviors of the intermediate α-ionyl-tetra-O-acetyl-β-d-glucoside (IAG) and IG were analyzed by thermogravimetry and online pyrolysis (Py)-gas chromatography–MS. Flavor release property of IG was investigated with cigarettes as the carrier. The results indicated that fracture temperature of glycosidic bond was about 200 °C for IAG, and was about 190 °C for IG. Py of IAG and IG could generate several aroma compounds such as megastigmatriene, α-ionol, α-ionone, and 3-oxo-α-ionol. IG added in cigarettes could be pyrolyzed to release α-ionol, α-ionone, and 3-oxo-α-ionone, and increase the release amount of megastigmatrienone in mainstream smoke during smoking. The release amount of characteristic flavor components in mainstream smoke remain stable after the cigarette sample with IG placed in standard condition for 30 days, and there was no significant difference in the single puff release amounts, which confirmed the flavor release stability and uniformity of IG under heating treatment.     

Synthesis and crystal structure of New Amminecopper(II) Nitrates: [Cu(NH3)2](NO3)2 and [Cu(NH3)](NO3)2

[Cu(NH₃)₂](NO₃)₂ ( I ) and [Cu(NH₃](NO₃)₂ ( II ) were synthesized by interaction of molten NH₄NO₃ with [Cu(NH₃)₄](NO₃)₂ and Cu(NO₃)₂ · 3 H₂O, respectively, at 180 to 195°C for 24 hr. According to X-Ray single crystal analysis, I is orthorhombic (sp. gr. Pbca) with a = 5.678(1), b = 9.765(2), c = 11.596(2) Å, Z = 4, R = 0.060; II is monoclinic (sp. gr. P2₁/c) with a = 6.670(1), b = 8.658(2), c = 9.661(2) Å, β = 101.78(2)°, Z = 4, R = 0.027. In both structures, the nearest coordination environment of Cu is a slightly distorted square formed by N (from NH₃) and O atoms (from NO₃ groups). The structure of I consists of centrosymmetrical [Cu(NH₃)₂](NO₃)₂ molecules linked by hydrogen bonds. The Cu? N and Cu? O distances are 1.98 and 2.01 Å, respectively. In II , the Cu? N distance is 1.95 Å, the Cu? O distances are 1.96, 2.02, and 2.03 Å. The [CuO₃NH₃] squares are connected by NO₃ bridges into zigzag chains, which are linked into layers by longer Cu? O interactions (2.31 Å). Obviously, the layers are additionally strengthened and held together by hydrogen bonds.     

Synthesis, structure, and properties of [RuNO(NH3)4OH][PtCl4] and [RuNO(NH3)4OH][PdCl4]

Double complex [RuNO(NH₃)₄OH][PtCl₄] (I) and [RuNO(NH₃)₄OH][PdCl₄] (II) salts have been prepared and explored with TGA, IR spectroscopy, powder and single crystals X-ray diffraction. Crystal phases of I and II are isostructural (space group Cmc2₁) and have the following crystal chemical characteristics: a = 8.106 Å, b = 18.190(3) Å, c = 8.097 Å, V = 1194.0 ų, Z = 4, ρ_calc = 3.077 g/cm³ (I), and a = 8.116 Å, b = 18.135 Å, c = 8.062 Å, V = 1186.5 ų, Z = 4, ρ_calc = 2.600 g/cm³ (II). The product of thermal decomposition of I in inert and hydrogen atmospheres is a substitution solid solution Pt_0.5Ru_0.5 with the parameter of the FCC unit cell a = 3.856(3) Å. Thermolysis of II affords two-phase mixtures of limited solid solutions of the metals featuring Ru-based HCP and Pd-based FCC cells. __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 48, No.1, pp.114–121, January–February, 2007.     

[M(NH3)5Cl]WO4 (M = Cr, Rh): Synthesis, crystal structure, thermal properties

By single crystal X-ray diffraction the crystal structure of a series of [M(NH₃)₅Cl]WO₄ (M = Cr, Rh) complex salts is determined. The features of thermal expansion of the single crystal of [Cr(NH₃)₅Cl]WO₄ are studied by low- and high-temperature X-ray diffractometry in the temperature range from ?173°C to +127°C. It is shown that with an increase in the temperature, W-O distances and ∠O-W-O bond angles equalize and the average W-O distances decrease by 0.012 Å. The thermal properties of the salts in different gaseous atmospheres are examined and the phase composition of the obtained products is studied.     

[Pd(NH3)4][IrBr6] Complex: Synthesis,X-ray Powder Diffraction Analysis,and Thermal Decomposition

The complex salt [Pd(NH₃)₄][IrBr₆] was synthesized and studied using X-ray powder diffraction, thermal and elemental analyses, and IR and Raman spectroscopy methods. Crystallographic parameters: a= 11.999 Å, b= 11.290 Å, c= 10.802 Å, V= 1463.3 ų, Z= 4, space group Cmca, (calcd) = 3.841 g/cm³. Thermolysis in an inert atmosphere runs through four stages to yield an equiatomic Pd–Ir solid solution as the final product.     

Synthesis, crystal structure and thermal properties of [Co(NH3)5Cl]MO4 (M = Mo, W)

Crystal structures of [Co(NH₃)₅Cl]MoO₄ and [Co(NH₃)₅Cl]WO₄ complex salts are determined by single crystal X-ray diffraction. It is demonstrated for both salts that within the temperature range T = ?123?20°C there is a negative thermal expansion (about 0.26%) towards the c axis of the orthorhombic unit cell (Pnma space group). Thermal properties of the salts are investigated. The phase composition of the products obtained on heating the salts in different gas atmospheres is studied.     

Double complex salts [Ni(NH3)6]3[Fe(CN)6]2 and [Ni(NH3)6]3[Cr(CNS)6]2: Synthesis and properties

The double complex salts [Ni(NH₃)₆]₃[Fe(CN)₆]₂ and [Ni(NH₃)₆]₃[Cr(CNS)₆]₂ were synthesized and their thermal decomposition in air was studied. The values of interplanar distances in crystal lattices were determined. The compounds are proposed as precursors for producing homogeneous bimetallic nanodimensional powders.     

[Ni(en)3](ReO4)2: Synthesis, crystal structure and thermal properties

The crystal structure of [Ni(en)₃](ReO₄)₂ (en is ethylenediamine) is studied: a = 8.3997(2)?, b = 15.6167(5)?, c = 14.2406(4)?, β = 100.378(1)°, V = 1837.46(9) OA³, P2₁/c space group, Z = 4, and d _x = 2.673 g/cm³. It is shown that packing of the complex cations can be considered as single-layer pseudohexagonal. Thermal decomposition of the salt in a hydrogen atmosphere at 550°C is used to obtain a mixture of nickel with a nanocrystalline Re_0.87Ni_0.13 solid solution (a = 2.733(2)?, c = 4.400(3)?, P6₃/mmc space group; CSR size is ∼14 nm).