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1.
The electrical conductivities of the compounds (CH 3NH 3) 2CuCl 4, (C 2H 5NH 3) 2CuCl 4 and (CH 2) 2(NH 3) 2CuCl 4 were measured in the temperature range which includes their structural phase transition. The values of the activation energies as calculated from the Arrhenius equation are reported. Confirmation of the phase transition temperatures is carried out using differential thermal analysis in the same temperature range as the conductivity measurements. 相似文献
2.
(C6H(14)N2)[NH4(ClO4)3] is a newly developed porous hybrid inorganic-organic framework material with easy access and excellent detonation performances,however,its thermal properties is still unclear and severely hampered further applications.In this study,thermal behaviors and non-isothermal decomposition reaction kinetics of(C6H(14)N2)[NH4(ClO4)3] were investigated systematically by the combination of differential scanning calorimetry(DSC) and simultaneous thermal analysis methods.In-situ FTIR spectroscopy technology was applied for investigation of the structure changes of(C6H(14)N2) NH4(ClO4)3]and some selected referents for better understanding of interactions between different components during the heating process.Experiment results indicated that the novel molecular perovskite structure renders(C6H(14)N2)[NH4(ClO4)3] better thermal stability than most of currently used energetic materials.Underhigh temperature s,the stability of the cage skeleton constructed by NH4^+and ClO4^-ions determined the decomposition process rather than organic moiety confined in the skeleton.The simple synthetic method,good detonation performances and excellent thermal properties make(C6H(14)N2)[NH4(ClO4)3] an ideal candidate for the preparation of advanced explosives and propellants. 相似文献
3.
The heat capacities of the tungsten oxides WO 3, W 20O 58, W 18O 49 and WO 2 have been measured over the temperature range 340–999 K using differential scanning calorimetry. The lower oxides were prepared by controlled reduction of WO 3 in H 2/H 2O gas atmospheres. Previous calorimetric work on WO 3 is confirmed in the temperature range 340–800 K, however, significant increases in heat capacity were observed in the range 800–999 K prior to the orthorhombic—tetragonal phase transition. W 20O 58 is shown to behave similarly to WO 3. A high temperture phase change is evident, however, this appears to be complete by 970–990 K. The measured values of heat capacity for W 18O 49 are in close agreement with estimated data for W 18O 49. There is no evidence of any phase transitions for this oxide in the temperature range studied. The heat capacity data for WO 2 confirm previous drop calorimetry measurements and give no evidence of any phase changes for WO 2 in the temperature range 340–990 K. 相似文献
4.
Thermodynamic properties of binary systems of C 60 with 1,2- and 1,3-dibromobenzenes have been studied by means of differential scanning calorimetry (DSC). Solid solvates with the compositions C 603(1,2-C 6H 4Br 2); C 602(1,3-C 6H 4Br 2) and C 600.6(1,3-C 6H 4Br 2) have been found. The solvates have been characterised by their enthalpies and temperatures of incongruent melting transition and in part by X-ray powder data. It has been shown that positional isomers 1,2- and 1,3- of the substituted benzenes formed two series of “typical” phase diagrams. Solubility behaviour of C 60 in positional isomers has been discussed. 相似文献
5.
A new organically templated metal sulfate has been synthesized and characterized. At room temperature, dabcodiium hexaaquacopper(II) bis(sulfate), (C 6H 14N 2)[Cu(H 2O) 6](SO 4) 2 crystallizes in the monoclinic symmetry (space group P2 1/ n) with the following unit cell parameters: a = 6.9533(2), b = 12.5568(2), c = 9.9434(2) Å; β = 90.526(1)° and Z = 2. Its crystal structure is built from isolated [Cu(H 2O) 6] 2+, and disordered ions linked together by a hydrogen-bonding network. The title compound undergoes a reversible phase transition of the first-order type at 265.7/281.8 K on heating–cooling runs. Below the phase transition temperature, the structure is fully ordered. 相似文献
6.
The structural development of the NiFe 2O 4 nanocrystals dispersed in a silica matrix was followed by IR and EPR spectroscopies of the dried gel 10NiO–10Fe 2O 3–90SiO 2 after heat treatment. The dried gel obtained at 200°C was amorphous, in which Fe 3+ and Ni 2+ ions were distributed in the pores of silica matrix. When the dried gel was heat treated at 400°C, NiFe 2O 4 clusters were partially formed, showing an enhanced interaction with the silica matrix. NiFe 2O 4 clusters were completely formed in silica matrix when the heat treatment was increased to 600°C, at which the interactions between the clusters and silica matrix reached a maximum. The formation reaction of NiFe 2O 4 clusters was accompanied by a rearrangement of the silica matrix network. Further increase of the heat treatment temperature to 800°C led to superparamagnetic single domain NiFe 2O 4 nanocrystals (ca. 4 nm) dispersed in the silica matrix with the elimination of the interactions between magnetic nanocrystals and silica matrix. 相似文献
7.
The thermal decompositions of two systems(NO.1,KClO 3(52.2%)/CuO(26.0%)/S(9.6%)/Mg-Al(3.5%)/C 6Cl 6(4.35%)) and NO.2,(KClO 3(52.2%)/CuO(26.0%)/S(9.6%)/Mg-Al(3.5%)/C 6Cl 6(4.35%)) are studied using Accelerating Rate Caorimeter (ARC).Temperature vs time curve and pressure vs time curve of reactions are shown in Fig.1 and Fig.2 respectively.The basic data including reaction time(1.3 and 7.3 min respectively),initial temperature (159 and 150℃ respectively),temperature at the maximum rate(272 and 272℃ respectively),the maximum pressure (420 and 190kPa respectively) and the activation energies(175.6 and 135.2 kJ mol-1 respectively) of the thermal decomposition are given to evaluate the safety of the two systems.Results indicate that system NO.2 is safer than NO.1.Compared with the traditional methods,ARC technique can be used to measure temperature and pressure of exothermic reaction concurrently,to find the tiny exothermicity and to determine the initial temperature of exothermic reaction. 相似文献
8.
LnCl 3 (Ln=Nd, Gd) reacts with C 5H 9C 5H 4Na (or K 2C 8H 8) in THF (C 5H 9C 5H 4 = cyclopentylcyclopentadienyl) in the ratio of 1 : to give (C 5H 9C 5H 4)LnCl 2(THF) n (orC 8H 8)LnCl 2(THF) n], which further reacts with K 2C 8H 8 (or C 5H 9C 5H 4Na) in THF to form the litle complexes. If Ln=Nd the complex (C 8H 8)Nd(C 5H 9C 5H 4)(THF) 2 (a) was obtained: when Ln=Gd the 1 : 1 complex [(C 8H 8)Gd(C %H 9)(THF)][(C 8H 8)Gd(C 5H 9H 4)(THF) 2] (b) was obtained in crystalline form. The crystal structure analysis shows that in (C8H8)Ln(C5H9C5H4)(THF)2 (Ln=Nd or Gd), the Cyclopentylcyclopentadieny (η5), cyclooctatetraenyl (η8) and two oxygen atoms from THF are coordinated to Nd3+ (or Gd3+) with coordination number 10. The centroid of the cyclopentadienyl ring (Cp′) in C5H9C5H4 group, cyclooctatetraenyl centroid (COTL) and two oxygens (THF) form a twisted tetrahedron around Nd3+ (or Gd3+). In (C8H8)Gd(C5H9C5H4)(THF), the cyclopentyl-cyclopentadienyl (η5), cyclooctatetraenyl (η8) and one oxygen atom are coordinated to Gd3+ with the coordination number of 9 and Cp′, COT and oxygen atom form a triangular plane around Gd3+, which is almost in the plane (dev. -0.0144 Å). 相似文献
9.
The harmonic frequencies and infrared intensities of C 9, C 11 and C 13 have been calculated using SCF and complete active space SCF (CASSCF) methods. The ordering of the harmonic frequencies in C 9 is predicted wrongly unless at least the π HOMO and LUMO are included in the active space. Infrared intensities depend crucially on the size of the active space. For linear odd-numbered clusters C 13 and larger, the computed SCF spectrum is qualitatively wrong. The recent observation of a band near 1809 cm −1 in the gas phase is explained using our CASSCF results on C 13. 相似文献
10.
Thermal displacement of coordinated nitriles RCN (R = CH 3, C 2H 5 or n-C 3H 7) in [C 5H 5Fe(L 2)(NCR)]X complexes (L 2 = P(OCH 3) 3) 2, (P(OC 6H 5) 3) 2 or (C 6H 5) 2PC 2H 4P(C 6H 5) 2 (DPPE)) by E(CH 3) 2 affords high yields of [C 5H 5Fe(L 2)(E(CH 3) 2)]X compounds (E = S, Se and Te; X = BF 4 or PF 6). Spectroscopic data and ligand displacement reactions are presented and discussed together with related observations on [C 5H 5Fe(CO) 2(E(CH 3) 2)]BF 4 compounds. The molecular structure of [C 5H 5Fe(P(OCH 3) 3) 2(S(CH 3) 2)]PF 6 was determined by a single-crystal X-ray diffraction study: monoclinic, space group P2 1/ n- C52h (No. 14) with a = 8.4064(12), b = 11.183(2), c = 50.726(8) Å, β = 90.672(13)° and Z = 8 molecules per unit cell. The coordination sphere of the iron atom is pseudo-tetrahedral with an Fe---S bond distance of 2.238 Å. 相似文献
11.
Potential energy surfaces of the reaction of SiH 2 and C 2H 2 (and C 2D 2) have been calculated by means of ab initio molecular orbital theory at the QCISD/6-311G++(2df, 2p)//MP2/6-31G(d, p) level with corrections for the triple excitations to the QCISD energies. The barrier heights for the two reaction channels of the adduct, thus calculated, were further utilized for the dynamical calculation of the rate constants in the framework of quantum statistical Rice-Ramsperger-Kassel theory. Contributions of the rate constants of the various pathways to the total rate constant ( KT) for the disappearance of the reactants are critically examined and compared with experiment. The pressure dependence of KT(C 2H 2) is primarily due to the formation of silirene. KT(C 2D 2) is consistently higher than KT(C 2H 2). The standard heat of formation of silirene is predicted to be 72.1 ± 3 kcal/mol. Rearrangement of silirene to vinylsilylene requires an activation energy smaller than that to silylacetylene. 相似文献
12.
(C 5Me 5) 2Sm(THF) 2 reacts with 1,2-epoxybutane in toluene to form, in addition to the toluene soluble [(C 5 Me 5) 2Sm] 2(μ-O), 1, the hexane soluble [(C 5Me 5) 2Sm(THF)] 2(μ-O), 2. In hexane, 2 loses THF to form 1 as a precipitate, but 1 cannot be converted to 2 by addition of THF at room temperature. Compound 1 does convert to 2 in low yield in THF at reflux. The reaction of (C 5Me 5) 2SM(phthalan) with 1,2-epoxybutane generates 1 and a phthalan analog of 2, [(C 5Me 5) 2Sm(phthalan)] 2(μ,-O), 3. Compound 2 reacts with Me 3CCN to form [(C 5Me 5) 2Sm(NCCMe 3)] 2(μ-O), 4, by displacement of THF. 相似文献
13.
The molecular structure (equilibrium geometry) and binding energy of the dimethylzinc (DMZn)-hydrogen selenide (H 2Se) adduct, (CH 3) 2Zn:SeH 2, have been computed with ab initio molecular orbital and density functional theory (DFT) methods and, where possible, compared with experimental results. The structure of the precursors DMZn and H 2Se are perturbed to only a small extent upon adduct formation. (CH 3) 2Zn:SeH 2 was found to be 3 kcal mol −1 less stable than the precursors at the B3LYP/6-311 + G(2 d, p)//B3LYP/6-311 + G(2 d, p) level of computation, indicating that the (CH 3) 2Zn:SeH 2 adduct is unlikely to be a stable gas-phase species under chemical vapour deposition conditions. Further calculations at the B3LYP/6-311 + G(2 d, p)//B3LYP/6-311 + G(2 d, p) level of computation suggest that the 1:2 adduct species, (CH 3) 2Zn:(SeH 2) 2, is much less stable than the 1:1 adduct and consequently the precursors by 19 kcal mol −1. 相似文献
14.
The pure rotational Raman spectra of C 214N 2 and C 215N 2 have been recorded photographically using a 3-metre spectrograph with a reciprocal linear dispersion of 1.4 cm −1 mm −1 at 488.0 nm and analysed to give the rotational and centrifugal distortion constants for both species. Corrections were applied to compensate for the effect of molecules in excited vibrational states on the pure rotational spectra. Comparisons are made with previous infrared vibration—rotational studies on these species and with previous Raman studies on C 214N 2. The following bond lengths were calculated: r0(C---N) = 116 ± 1 pm; r0(C---C) = 138 ± 2 pm. 相似文献
15.
[Re 2(Ala) 4(H 2O) 8](ClO 4) 6 (Re=Eu, Er; Ala=alanine) were synthesized, and the low-temperature heat capacities of the two complexes were measured with a high-precision adiabatic calorimeter over the temperature range from 80 to 370 K. For [Eu 2(Ala) 4(H 2O) 8](ClO 4) 6, two solid–solid phase transitions were found, one in the temperature range from 234.403 to 249.960 K, with peak temperature 243.050 K, the other in the range from 249.960 to 278.881 K, with peak temperature 270.155 K. For [Er 2(Ala) 4(H 2O) 8](ClO 4) 6, one solid–solid phase transition was observed in the range from 270.696 to 282.156 K, with peak temperature 278.970 K. The molar enthalpy increments, Δ Hm, and entropy increments,Δ Sm, of these phase transitions, were determined to be 455.6 J mol −1, 1.87 J K −1 mol −1 at 243.050 K; 2277 J mol −1, 8.43 J K −1 mol −1 at 270.155 K for [Eu 2(Ala) 4(H 2O) 8](ClO 4) 6; and 4442 J mol −1, 15.92 J K −1 mol −1 at 278.970 K for [Er 2(Ala) 4(H 2O) 8](ClO 4) 6. Thermal decompositions of the two complexes were investigated by use of the thermogravimetric (TG) analysis. A possible mechanism for the thermal decomposition is suggested. 相似文献
16.
The ruthenium(II) complex Ru(CO) 2(NH 2(NH 2CH 2C 6H 5) 2(Si(C 6H 5)(CH 3) 2)I has been prepared by the reaction of Ru(CO) 4(Si(C 6H 5)(CH 3) 2)I with benzylamine. Two-dimensional homonuclear 1H NMR experiments examine the scalar coupling of the enantiotopic amino and methylene protons of the benzylamine ligand. X-ray analysis of Ru(CO) 2(NH 2CH 2C 6H 5) 2(Si(C 6H 5)(CH 3) 2)I·1/3C 5H 12 (triclinic; P
; a = 14.266(4), b = 15.748(5), c = 20.082(6) Å; = 94.38(3), β = 96.30(2), γ = 101.52(2)°) indicates three crystallographically unique complexes form a clathrate with a pentane guest. 相似文献
17.
The spectral analysis indicates that all isomers of C 60O, C 70O and C 60O 2 have an epoxide-like structure (an oxygen atom bridging across a C–C bond). According to the geometrical structure analysis, there are two isomers of fullerene monoxide C 60O (the 5,6 bond and the 6,6 bond), eight isomers of fullerene monoxide C 70O and eight isomers of fullerene dioxide C 60O 2. In order to simulate the real reaction conditions at 300 K, the calculation of the different isomers of C 60O, C 60O 2 and C 70O fullerene oxides was carried out using the semiempirical molecular dynamics method with two different approaches: (a) consideration of the geometries and thermodynamic stabilities, and (b) consideration of the ozonolysis mechanism. According to the semiempirical molecular dynamic calculation analysis, the probable product of this ozonolysis reaction is C 60O with oxygen bridging over the 6–6 bond (C 2v). The most probable product in this reaction contains oxygen bridging across in the upper part of C 70 (6–6 bond in C 70O-2 or C 70O-4) an epoxide-like structure. C 60O 2-1, C 60O 2-3 and C 60O 2-5 are the most probable products for the fullerene dioxides. All of these reaction products are consistent with the experimental results. It is confirmed that the calculation results with the semiempirical molecular dynamics method are close to the experimental work. The semiempirical molecular dynamics method can offer both the reaction temperature effect by molecular dynamics and electronic structure, dipole moment by quantum chemistry calculation. 相似文献
18.
Treatment of 1,2- trans-C 5H 8(PCl 2) 2 with 1,2-C 2H 4(NHPr- i) 2 gave the C2-symmetric perhydro-1,6,2,5-diazaphosphocine C 5H 8{P(Cl)N(Pr- i)CH 2} 2- cyclo, which produced dissymmetric C 5H 8(PPh 2){P[N(Pr- i)CH 2] 2- cyclo} on further reaction with PhMgBr. Cleavage of the P---N bonds with gaseous HCl afforded C 5H 8(PPh 2)(PCl 2), which was converted to C 5H 8(PPh 2){P(OPh) 2} 2 by reaction with phenol. All chiral P, P derivatives were obtained as racemates as well as resolved (1 R,2 R)- and (1 S,2 S)-enantiomers. 相似文献
19.
In comparison to conventional C 18 phases, C 30 phases exhibit superior shape selectivity for the separation of isomers of carotenoids and vitamins. To obtain this enhanced recognition capability the HPLC separation must be performed at a well-defined temperature. At higher temperatures the capability of differentiating between different stereochemical isomers is lost, resulting in peak coelution. This separation behaviour is primarily dependent upon the organisation of the C 30 alkyl chains on the silica surface which can be visualised as two domains, the more ordered domain containing relatively rigid n-alkyl groups with trans conformations and the less ordered environment containing more flexible n-alkyl groups with gauche conformations. The ratio between trans vs. gauche conformations of the n-alkyl groups directs the shape selectivity of the C 30 phase. The temperature-dependent interconversion of trans to gauche conformations can be monitored by temperature-dependent solid-state nuclear magnetic resonance (NMR) and suspended-state NMR measurements and visualised by molecular modelling calculations. Thus a direct correlation between chromatographic and physicochemical properties of C 30 bonded phases is possible. 相似文献
20.
During the determination of the crystal structure of [(CO) 5CrNCN(C 2H 5) 2] by neutron diffraction, a remarkable te temperature-dependance of the intensity of three reference reflections between 100 and 300 K was accidentally observed. In order to try to understand the nature of this phenomenon, the behaviour of this compound as a function of the temperature has been studied by differential calorimetry, and by power and single crystal X-ray diffraction methods. These experiments show neither a phase transition nor a crystal space group modification. The experimental results, supported by a simplified model, suggest a rotational disorder of the methyl groups near room temperature. 相似文献
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