Synthesis and Properties of [Ba(CHZ)(BT)(H2O)2]n as a New Energetic Coordination Compound

In order to enhance the thermal stability of the barium salt of 5,5′‐bistetrazole (H₂BT), carbohydrazide (CHZ) was used to build [Ba(CHZ)(BT)(H₂O)₂]_n as a new energetic coordination compound by using a simple aqueous solution method. It was characterized by FT‐IR spectroscopy, elemental analysis, and single‐crystal X‐ray diffraction. The crystal belongs to the monoclinic P2₁/c space group [a = 8.6827(18) Å, b = 17.945(4) Å, c = 7.2525 Å, β = 94.395(2)°, V = 1126.7(4) ų, and ρ = 2.356 g · cm^–3]. The Ba^II cation is ten‐coordinated with one BT^2–, two shared carbohydrazides, and four shared water molecules. The thermal stabilities were investigated by differential scanning calorimetry (DSC) and thermal gravity analysis (TGA). The dehyration temperature (T_dehydro) is at 187 °C, whereas the decomposition temperature (T_d) is 432 °C. Non‐isothermal reaction kinetics parameters were calculated by Kissinger's method and Ozawa's method to work out E_K = 155.2 kJ · mol^–1, lgA_K = 9.25, and E_O = 158.8 kJ · mol^–1. The values of thermodynamic parameters, the peak temperature (while β → 0) (T_p0 = 674.85 K), the critical temperature of thermal explosion (T_b = 700.5 K), the free energy of activation (ΔG^≠ = 194.6 kJ · mol^–1), the entropy of activation (ΔS^≠ = –66.7 J · mol^–1), and the enthalpy of activation (ΔH^≠ = 149.6 kJ · mol^–1) were obtained. Additionally, the enthalpy of formation was calculated with density functional theory (DFT), obtaining Δ_fH°₂₉₈ ≈ 1962.6 kJ · mol^–1. Finally, the sensitivities toward impact and friction were assessed according to relevant methods. The result indicates the compound as an insensitive energetic material.     

Synthese,Struktur und Reaktionen von Vanadiumsäureestern VO(OR)3: Umesterung und Reaktion mit Oxalsäure

Synthesis, Structure, and Reactions of Vanadium Acid Esters VO(OR)₃: Transesterification and Reaction with Oxalic Acid The reaction of tert.‐Butyl Vanadate VO(O‐tert.Bu)₃ ( 1 ) with H₂C₂O₄ in the primary alcohols ethanol and propanol results in the formation of (ROH)(RO)₂OV^V(C₂O₄)V^VO(OR)₂(HOR) (with R = C₂H₅ 2 and R = C₃H₇ 3 ). Compounds 2 and 3 are the first structurally characterized neutral, binuclear oxo‐oxalato‐complexes with pentavalent vanadium. The two vanadium atoms are connected by a bisbidentate oxalate group. The {VO₆} coordination at each vanadium site is completed by a terminal oxo group, an alcohol ligand and two alcoxide groups. The binuclear molecules are connected to chains by hydrogen bonding. In the case of 2 a reversible isomorphic phase transition in the temperature range of –90 °C to –130 °C is observed. From methanolic solution the polymeric Methyl Vanadate [VO(OMe)₃] ( 4 ) was obtained by transesterification. A report on the crystal structures of 1 , 2 and 3 as well as a redetermination of the structure of 4 is given. Crystal data: 1, orthorhombic, Cmc2₁, a = 16.61(2) Å, b = 9.274(6) Å, c = 10.784(7) Å, V = 1662(2) ų, Z = 4, d_c = 1.144 gcm^–1; 2 (–90 ° C) , monoclinic, I2/a, a = 33.502(4) Å, b = 7.193(1) Å, c = 15.903(2) Å und β = 143.060(3)°, V = 2303(1) ų, Z = 4, d_c = 1.425 gcm^–1; 2 (–130 ° C) , monoclinic, I2/a, a = 33.274(4) Å, b = 7.161(1) Å, c = 47.554(5) Å, β = 142.798(2)°, V = 6851(1) ų, Z = 12, d_c = 1.438 gcm^–1; 3 , triklinic, P1, a = 9.017(5) Å, b = 9.754(5) Å, c = 16.359(9) Å, α = 94.87(2)°, β = 93.34(2)°, γ = 90.42(2)°, V = 1431(1) ų, Z = 2, d_c = 1.340 gcm^–1; 4 , triklinic, P1, a = 8.443(2) Å, b = 8.545(2) Å, c = 9.665(2) Å, α = 103.202(5)°, β = 96.476(5)°, γ = 112.730(4)°, V = 610.2(2)ų, Z = 4, d_c = 1.742 gcm^–1.     

Die Kristallstruktur von Kaliummonomethylcarbonat

Crystal Structure of Potassium Monomethylcarbonate Potassium monomethylcarbonate KCH₃CO₃ was obtained from reaction of dimethylcarbonate with potassium hydroxide in methanole. The crystal structure was determined (triclinic, P1 (no. 2), Z = 2, a = 380.9(2) pm, b = 558.9(3) pm, c = 985.3(3) pm, α = 100.71(2)°, β = 90.06(3)°, γ = 92.48(3)°, V = 205.9(2) · 10⁶ pm³, wR(F²) = 0.054, wR_obs(F) = 0.022). Structural relations between potassium monomethylcarbonate and potassium hydrogencarbonate are discussed.     

Ein neues Kaliumhydrogensulfat,K(H3O)(HSO4)2 — Synthese und Struktur

A New Potassium Hydrogensulfate, K(H₃O)(HSO₄)₂ — Synthesis and Structure Single crystals of the new compound K(H₃O)(SO₄)₂ are synthesized from the system potassium sulfate/sulfuric acid. The up to day not described compound crystallizes in the monoclinic space group P2₁/c with the unit cell parameters a = 7.203(1) b = 13.585(2) and c = 8.434(1) Å, β = 105.54(1)°, V = 795.1 ų, Z = 4 and D_x = 2.107 g · cm^?3. There are two crystallographically different tetrahedral SO₃(OH) anions. The first kind S1 tetrahedra forms dimers, whereas the second kind S2 forms infinite chains bonded via hydrogen bridges. The S1 dimers are linked to the S2 chains via oxonium ions (hydrogen bonds). Potassium is coordinated by 8 oxygen atoms which belong to four different SO₃(OH) tetrahedra. These potassium oxygen polyhedra are connected by common edges forming chains running parallel z.     

Protonenlagen bei Kaliumtetraamidozinkat,K2Zn(NH2)4

Positions of the Protons in Potassium Tetraamidozincate, K₂Zn(NH₂)₄ X-ray single crystal data for K₂Zn(NH₂)₄ allowed the determination of the so far unknown positions of the protons: P1 , Z = 2, a = 6.730(1) Å, b = 7.438(1) Å, c = 8.019(2) Å, α = 72.03(2)°, β = 84.45(2)°, γ = 63.82(1)°, Z(F₀) with (F₀)² ≥ 3σ(F₀)² = 2166, Z(parameters) = 96, R/R_W = 0.032/0.039. In the structure of K₂Zn(NH₂)₂ the amide ions are nearly hexagonal close packed. One layer of octahedral holes parallel to (010) is fully occupied by potassium atoms and zinc is in an ordered way in a quarter of the tetrahedral holes of the next layer. The orientation of the protons of the amide ions is characteristic for this type of structure (filled up CdI₂ type).     

Dimorphism of K4Ta2S11: Syntheses,Crystal Structures,and Properties of two Alkali Metal Tantalum Sulfides

The new ternary potassium tantalum polysulfide K₄Ta₂S₁₁ crystallizing in the triclinic space group P1 with a = 7.465(2), b = 11.441(3), c = 11.534(3) Å, α = 68.66(2), β = 86.59(2) and γ = 83.09(2)° represents a second modification of the already known orthorhombic form, space group Pca2₁ with a = 13.166(2), b = 7.449(2) and c = 18.000(2) Å. The interatomic distances and angles within the Ta₂S₁₁^4– anions of both forms are very similar, but significant differences are observed for the S…S distances between neighboured anions. Temperature dependent single crystal X‐ray experiments yield thermal expansion coefficients of 9.88(30) and 9.44(4) 10^–5 K^–1 for the triclinic and orthorhombic compound, respectively. The higher density for the orthorhombic form indicates that this modification is the thermodynamical more stable form at low temperatures. This assumption is supported by calculations of the electrostatic contributions to the lattice energies using MAPLE (Madelung part of lattice energy). The lattice energy of the orthorhombic form is about 46 kJ mol^–1 larger than that of the triclinic modification. Small differences are observed in the MIR (Medium Infrared Range) spectra of the two dimorphs which correlate well with the slightly different Ta = S bond lengths within the Ta₂S₁₁^4– anions. The compounds were also characterized using UV/Vis reflectance spectroscopy.     

High‐performance liquid chromatographic enantioseparation of isoxazoline‐fused 2‐aminocyclopentanecarboxylic acids on a chiral ligand‐exchange stationary phase

The application of a chiral ligand‐exchange column for the direct high‐performance liquid chromatographic enantioseparation of unusual β‐amino acids with a sodium N‐((R)‐2‐hydroxy‐1‐phenylethyl)‐N‐undecylaminoacetate‐Cu(II) complex as chiral selector is reported. The investigated amino acids were isoxazoline‐fused 2‐aminocyclopentanecarboxylic acid analogs. The chromatographic conditions were varied to achieve optimal separation. The effects of temperature were studied at constant mobile phase compositions in the temperature range 5–45°C, and thermodynamic parameters were calculated from plots of lnk or lnα versus 1/T. Δ(ΔH°) ranged from –2.3 to 2.2 kJ/mol, Δ(ΔS°) from –3.0 to 7.8 J mol^?1 K^?1 and –Δ(ΔG°) from 0.1 to 1.7 kJ/mol, and both enthalpy‐ and entropy‐controlled enantioseparations were observed. The latter was advantageous with regard to the shorter retention and greater selectivity at high temperature. Some mechanistic aspects of the chiral recognition process are discussed with respect to the structures of the analytes. The sequence of elution of the enantiomers was determined in all cases.     

Synthese und Struktur von [ImNCS2K] (ImN = 1,3-Dimethylimidazolin-2-imino): ein neuartiges Kaliumdithiocarbiminat

Synthesis and Structure of [ImNCS₂K] (ImN = 1,3-Dimethylimidazoline-2-imino): a Novel Potassium Dithiocarbiminate The reaction of the 2-iminoimidazoline 4 with KMe gives the potassium imidate 7 from which the potassium 1,1-dithiolate 8 is obtained in almost quantitative yield. Crystals of C₆H₈N₃S₂K · 1/6 CH₃CN ( 8 · 1/6 CH₃CN) are triclinic, space group P1 , Z = 6, a = 10.988(4), b = 13.597(8), c = 13.622(9) Å, α = 113.003, β = 105.53(3), γ = 105.62(3)°, V = 1636.90 ų. The structure consists of a complicated 3-dimensional framework in which the K₂ units bridged by the four sulfur atoms of two thiolate ligands are connected by nitrogen and sulfur bridges.     

Syntheses,Crystal Structures,Optical and Thermal Properties of Two New Zirconium Polyselenides (K8Zr6Se30) Containing One‐dimensional Anionic Chains

Two new ternary compounds with composition K₈Zr₆Se₃₀ were prepared by reacting zirconium powder in potassium polyselenide melts. Both compounds crystallize in the triclinic space group P1 with a = 12.391(1) Å, b = 14.897(2) Å, c = 15.253(2) Å, α = 73.149(9)°, β = 76.330(9)°, γ = 70.023(9)° and V = 2502.8(3) ų for I and a = 12.2793(8) Å, b = 14.887(1) Å, c = 22.512(2) Å, α = 72.714(7)°, β = 88.475(7)°, γ = 70.748(7)° and V = 3698.1(4) ų for II . Their structures consist of infinite linear one‐dimensional anionic chains running parallel to [110], which are connected by the potassium cations. The structural differences between both compounds originate from some disordering in one of the two crystallographically independent anionic chains of each compound, in which Se^2– anions are exchanged by Se₂^2– anions to some degree. The optical band gap was determined by UV/Vis reflectance spectra to 1.91 eV for I and 1.81 eV for II . Differential scanning calorimetry investigations show, that II decomposes reversibly at about 500 °C to K₂Se₃ and ZrSe₃. On cooling II is formed again. These results are confirmed by the direct reaction between K₂Se₃ and ZrSe₃ which leads directly to II .     

Die Kristallstruktur der Tieftemperaturmodifikation von Ag5Te2Cl

The Crystal Structure of the Low‐Temperature Form of Ag₅Te₂Cl Crystals of trimorphic Ag₅Te₂Cl were obtained by solid state reaction from a stoichiometric mixture of silver, tellurium, and tellurium(IV)chloride (480 °C, 4–10 days). The crystals were cooled down to –80 °C without decomposition and data collection was carried out at this temperature. The low temperature form of the title compound crystallizes in space group P2₁/c with lattice constants of a = 19.359(1) Å, b = 7.713(1) Å, c = 19.533(1) Å, β = 90.6°(1), V = 2916.4(1), and Z = 16. The refinement converged to residual values of R₁ = 0.0381 and wR₂ = 0.0847, respectively. Te and Cl atoms form empty, distorted octahedra interconnected by common vertices to give a 3D‐network. Ag atoms form clusters with Ag–Ag distances between 2.83 Å and 3.10 Å.     

Kaliumhydrogensulfat-Dihydrogensulfat,K(HSO4)(H2SO4) – Synthese und Kristallstruktur

Potassium Hydrogensulfate Dihydrogensulfate, K(HSO₄)(H₂SO₄) – Synthesis and Crystal Structure Single crystals with the composition KH₃(SO₄)₂ have been synthesized from the system Potassium sulfate/sulfuric acid. The hitherto crystallographically not investigated compound crystallizes in the monoclinic space group P2₁/c (14) with the unit cell parameters a = 7.654(3), b = 11.473(5) and c = 8.643(3) Å, β = 112.43(3)°, V = 701.6 ų, Z = 4 and D_x = 2.22 g · cm^?3. The structure contains two types of tetrahedra, SO₃(OH) and SO₂(OH)₂. These tetrahedra form tetramers via hydrogen bonds consisting of both, two SO₃(OH) and two SO₂(OH)₂ tetrahedra. The tetramers are linked to each other via hydrogen bonds. Potassium is coordinated by 9 oxygen atoms which belong to both kinds of tetrahedra. These potassium oxygen polyhedra are connected by common faces forming chains running parallel z.     

Die Kristallstruktur von K[F5W(≡NCl)]

Crystal Structure of K[F₅W(≡NCl)] Orange single crystals of K[F₅W(≡NCl)] have been formed as a by‐product from the reaction of tungsten nitrido chloride, WNCl₃, with Me₃SnF in the presence of potassium fluoride in toluene suspension. K[F₅W(≡NCl)] crystallizes in the monoclinic space group P2₁/c with four formula units per unit cell. Lattice dimensions at –83 °C: a = 1145.9(3), b = 770.4(2), c = 772.5(2) pm, β = 99.91(1)°, R₁ = 0.0742. The compound forms an ionic structure with octahedral [F₅W(≡NCl)]^– ions with a nearly linear arrangement of the N‐chloroimido ligand group W≡N–Cl (bond angle 173°, WN distance 174 pm). The K⁺ ions link the anions via K…F contacts and coordination number eight to form double layers along [100]. The layers itself are associated by short bounding Cl…F contacts of 279 pm.     

Struktur und magnetische Eigenschaften von Bis{3‐amino‐1,2,4‐triazolium(1+)}pentafluoromanganat(III): (3‐atriazH)2[MnF5]

Structure and Magnetic Properties of Bis{3‐amino‐1,2,4‐triazolium(1+)}pentafluoromanganate(III): (3‐atriazH)₂[MnF₅] The crystal structure of (3‐atriazH)₂[MnF₅], space group P1, Z = 4, a = 8.007(1) Å, b = 11.390(1) Å, c = 12.788(1) Å, α = 85.19(1)°, β = 71.81(1)°, γ = 73.87(1)°, R = 0.034, is built by octahedral trans‐chain anions [MnF₅]^2–_∞ separated by the mono‐protonated organic amine cations. The [MnF₆] octahedra are strongly elongated along the chain axis (<Mn–F_ax> 2.135 Å, <Mn–F_eq> 1.842 Å), mainly due to the Jahn‐Teller effect, the chains are kinked with an average bridge angle Mn–F–Mn = 139.3°. Below 66 K the compound shows 1D‐antiferromagnetism with an exchange energy of J/k = –10.8 K. 3D ordering is observed at T_N = 9.0 K. In spite of the large inter‐chain separation of 8.2 Å a remarkable inter‐chain interaction with |J′/J| = 1.3 · 10^–5 is observed, mediated probably by H‐bonds. That as well as the less favourable D/J ratio of 0.25 excludes the existence of a Haldene phase possible for Mn³⁺ (S = 2).     

Wasserstoffbrückenbindungen in den Monoammoniakaten von Kalium‐ und Caesiumamid

Hydrogen Bonds in the Monoammoniates of Potassium and Cesium Amide X‐ray structure determination was carried out on the monoammoniates of potassium and cesium amide. Crystals of KNH₂ · NH₃ were grown from liquid NH₃ at 50 °C > T > 20 °C. They crystallize in the cold part of a pressure resistant glass apparatus. Single crystals of CsNH₂ · NH₃ were obtained by zone‐melting at —30 °C in x‐ray capillaries. The following data characterize the crystal chemistry of the compounds: KNH₂ · NH₃ Cmc2₁, Z = 4 21 °C a = 3, 938(1) Å, b = 10, 983(3) Å, c = 5, 847(1) Å CsNH₂ · NH₃ Pnma, Z = 4 30 °C a = 7, 103(1) Å, b = 5, 390(1) Å, c = 10, 106(2) Å For CsNH₂ · NH₃ all hydrogen atom positions were successfully refined. The structure of both ammoniates may be described by a distorted hexagonal close packed arrangement of cations with the NH₃ molecules in the octahedral and the NH₂^— anions in the trigonal bipyramidal interstices. The three H atoms of the NH₃ molecules are involved in hydrogen bridge bonds to two amide ions with d(N(NH₃)···N(NH₂^—)) = 2.60Å for the K and 3.19Å for the Cs compound and to a further NH₃ molecule with d(N(NH₃)···N(NH₃)) = 2.98Å for the K and 3.56Å for the Cs compound. Structural relationship of the ammoniates to the monohydrates of KOH and RbOH is discussed.     

Pseudodimorphism of the Trans-9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboxylic Acid Clathrates with Acetic and Propionic Acids

The versatile host compound trans-9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboxylic acid (1) forms under ambient conditions isostructural complexes with acetic and propionic acids being true clathrates without host-guest type H-bonds. A new modification of the clathrate between 1 and acetic acid (1a) is obtained at sub-room temperature (5 °C) while for preparation of the new crystal form of the clathrate with propionic acid (1b) crystallization temperature should be increased up to 50 °C. Crystal structures of the pseudodimorphs show that homo carboxylic acid dimers existing in the conventional phases are also observed here, demonstrating the new compounds to be of same clathrate type. Crystal data: for 1a: triclinic P-1, a = 8.626(2) Å, b = 9.073(2) Å, c = 12.042(2) Å, α = 76.34(3)°, β = 77.41(3)°, γ = 84.13(3)°, V = 892.5(4) ų, Z = 2, R = 0.0446 for 3171 reflections; for 1b: monoclinic C2/c, a = 13.268(3) Å, b = 12.636(3) Å, c = 21.786(4) Å, β = 90.56(3)°, V = 3652.3(14) ų, Z = 8, R = 0.0618 for 2365 reflections.     

K4Au8Ga: eine Auffüllungsvariante des MgCu2‐Typs

K₄Au₈Ga: a Filling Variant of the MgCu₂ Type Black, brittle single crystals of K₄Au₈Ga were obtained as the main product of the reaction of potassium azide with gold sponge and gallium at T = 770 K. The structure of the compound (space group C2/m, Z = 4, a = 20.850(4) Å, b = 5.630(1) Å, c = 10.912(2) Å, β = 97,45(2)°) was determined from X‐ray single‐crystal diffractometry data. K₄Au₈Ga crystallizes in a filling variant of the MgCu₂ type. The gold atoms form a [Au_4/2]‐framework. One quarter of the tetrahedra is filled by gallium. The potassium atoms are placed in channel‐like cavities of the Au–Ga partial structure.     

The Crystal Structures of the Room Temperature and the Low Temperature Phase of Dimethylammonium Trifluoromethanesulfonate

Dimethylammonium trifluoromethanesulfonate 1 was synthesized by reaction of trifluoromethanesulfonic acid with an excess of dimethylamine. A temperature variable synchrotron measurement on the polycrystalline substance reveals that 1 passes through a phase transition below room temperature. The transition occurs in the temperature range of 282–285 K on heating and 272–280 K on cooling as determined by DSC. The room temperature phase crystallizes in space group Cmca (a = 11.031(6) Å, b = 18.466(14) Å, c = 8.173(9) Å, V = 1665(2) ų, Z = 8) and the low temperature phase in space group P 2₁/c (a = 8.8717(18) Å, b = 8.0838(16) Å, c = 10.968(2) Å, β = 92.128(4)°, V = 786.0(3) ų, Z = 4). The structures of both phases were determined by single crystal X‐ray diffraction, but refinement did not yield satisfactory residuals for the low temperature phase because of twinning of the crystal. It was, therefore, independently solved from the synchrotron powder diffraction data using rigid body models of the constituent ions and ab‐initio direct space methods. Both, the CF₃ group and the SO₃ group of the triflate ion, are rotationally disordered around the S–C bond, in the room temperature phase. In the low temperature phase, the triflate ion is well localized. Like in the alkali metal triflates, the triflate ions are arranged in double layers with the hydrophobic trifluoromethyl groups and the sulfonate groups, respectively, pointing towards each other. The dimethylammonium ion is located closer to the sulfonate group with contacts indicating hydrogen bonding. The packing in both phases is of the topological CsCl structure type.     

Kaliumamidotrioxogermanate(IV) – Wasserstoff-Brückenbindungen in K3GeO3NH2 und K3GeO3NH2 · KNH2

Potassium Amido Trioxo Germanates(IV) – Hydrogen Bridge Bonds in K₃GeO₃NH₂ and K₃GeO₃NH₂ · KNH₂ Colorless crystals of K₃GeO₃NH₂ and of K₃GeO₃NH₂ · KNH₂ were obtained by the reaction of KNH₂ with GeO₂ in supercritical ammonia at 450°C and p = 6 kbar in high-pressure autoclaves within 15 resp. 5 days. The crystal structures of both compounds were solved by X-ray single crystal methods. K₃GeO₃NH₂: P1 , a = 6.390(1) Å, b = 6.684(1) Å, c = 7.206(1) Å, α = 96.47(1)°, β = 101.66(1)°, γ = 91.66(1)°, Z = 2, R/R_w = 0.020/0.022, N(I) ≥ 2σ(I) = 3023, N(Var.) = 82 K₃GeO₃NH₂ · KNH₂: P2₁/c, a = 10.982(6) Å, b = 6.429(1) Å, c = 12.256(8) Å, β = 106.12(1)°, Z = 4, R/R_w = 0.022/0.029, N(F) ≥ 3σ(F) = 1745, N(Var.) = 107. In K₃GeO₃NH₂ tetrahedral ions GeO₃NH₂^3? are connected to chains by N? H …? O bridge bonds with 2.18 Å ≤ d(H …? O) ≤ 2.40 Å for d(N? H) ? 1.0 Å and by potassium ions while in K₃GeO₃NH₂ · KNH₂ bridge bonds between NH₂ groups of GeO₃NH₂^3? and NH₂^? ions as acceptors occur with 2.41 Å ≤ d((N? )H …? NH₂^?) ≤ 2.61 Å for d(N? H) ? 1.0 Å.     

Synthesis and Properties of [Cd(HTRTR)2(H2O)4](HTNR)2 as an Energetic Complex

The energetic complex, [Cd(HTRTR)₂(H₂O)₄](HTNR)₂ {HTRTR = 4‐[3‐(1,2,4‐triazol‐yl)‐1,2,4‐triaozle; HTNR^– = styphnic acid anion) was synthesized and characterized by FT‐IR spectroscopy, elemental analysis, and single‐crystal X‐ray diffraction. It crystallizes triclinic in space group P$\bar{1}$ [a = 8.156(2) Å, b = 8.374(2) Å, c = 13.267(4) Å, α = 84.925(11)°, β = 87.016(11)°, γ = 63.683(5)°, V = 808.9(4) ų, ρ = 1.940 g · cm^–3]. The Cd^II ion is six‐coordinate with two HTRTRs and four water molecules. The thermal stabilities were investigated by differential scanning calorimetry (DSC). Non‐isothermal reaction kinetic parameters were calculated by Kissinger's and Ozawa‐Doyle's methods to obtain E_K = 144.0 kJ · mol^–1, lgA_K = 14.22, and E_O = 144.3 kJ · mol^–1. The values of thermodynamic parameters, the peak temperature while β→0 (T_p0), free energy of activation (ΔG^≠), entropy of activation (ΔS^≠), and enthalpy of activation (ΔH^≠) were obtained. Additionally, the enthalpy of formation was calculated by Hess's law on the basis of the experimental constant‐volume heat of combustion measured by bomb calorimetry, obtaining Δ_fH°₂₉₈ = 4985.5 kJ · mol^–1. Finally, the sensitivities toward impact and friction were assessed according to relevant methods. The result indicates it as an insensitive energetic material.     

Synthesis and characterization of new soluble thermally stable poly(azomethine‐ether‐imide)s: discerning the possibility for high temperature applications

A new series of polyimides was synthesized by the condensation of monomers (azomethine‐ether diamine, DA‐1 and DA‐2) with pyromelliticdianhydride (PMDA), 3,4,9,10‐perylenetetracarboxylic dianhydride (PD) and 3,3′4,4′‐benzophenonetetracarboxylic dianhydride (BD). The structural explications of monomers and polyimides was conducted by FT‐IR, ¹H NMR and elemental analysis. All polyimides were found soluble in polar aprotic solvents and found to be semicrystalline in nature confirmed by XRD. The inherent viscosities were found in the range of 0.67–0.77 g/dl. %. Average molecular weight (M_W) and number average molecular weight (Mn) of the polyimides were found in the range of 5.72 × 10⁵ g/mol–6.58 × 10⁵ g/mol and 3.79 × 10⁵ g/mol 4.11 × 10⁵ g/mol respectively. The polyimides exhibited excellent thermal properties having a glass transition temperature T_g in the range of 230–290°C and the 10% weight loss temperature was above 450°C. The values of thermodynamic parameters, activation energy, enthalpy and entropy fall in the range of 45.2–53.90 kJ/mol, 43.5–52.30 kJ/mol and 0.217 kJ/mol k to 0.261 kJ/mol k respectively. Copyright © 2015 John Wiley & Sons, Ltd.