首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 70 毫秒
1.
The self-diffusion coefficients of water in active carbon (AC) having relatively wide micropores increase in direct proportion to the degree of filling. The self-diffusion coefficients D of adsorbed C6H6, C6F6, C6H12, and H2O molecules at 298 K do not depend on the size of the molecules and are larger, the greater the mobility of the molecules in the free liquids. The self-diffusion activation energy of the adsorbed molecules varies in the order: H2O>C6F6> C6H12 C6H14. C6H14. For H2O and C6H6 the activation energy increases as the characteristic size of the micropores of the AC increases.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 1949–1951, September, 1989.  相似文献   

2.
Carbon-13 chemical shifts, spin-lattice relaxation times and nuclear Overhauser enhancement factors at 28°C are reported for a series of polyfluoroaliphatic compounds :
, and perfluoroalkyl nonionic surfactants CmF2m+1CH2(OC2H4)nOH with m = 6, 7 and n = 3, 4, 5, 6 and C6F13CH2CH2CONH(C2H4O)nH with n = 3, 4. The influence of the perfluoroalkyl group on the 13C chemtcal shifts of the neighbouring hydrogenated carbons is discussed in terms of hyperconjugative type interactions between lone electron pairs on fluorine and the neighbouring CC or CO bond. Relaxation data show similar flexibilities of the fluorinated chains in the different molecules investigated. Nonionic surfactants exhibit segmental motions in both the hydrophobic perfluoroalkyl and the hydrophilic polyoxyethylene chains ; these motions appear to be similar to those of the analogous hydrogenated surfactants.  相似文献   

3.
Experimental data are presented on the spectral (ESR, IR, and optical) and thermochemical characteristics of a complex between the (Si–O)3Si.radical and an N2O molecule. The rate constants of separate reactions in the systems (Si–O)3Si.+ N2O and (Ge–O)3Ge.+ N2O are found. The results of quantum chemical calculations of potential energy surfaces and spectral characteristics are presented for the following systems: H.+ N2O, H3C.+ N2O, H3Si.+ N2O, F2HSi.+ N2O, F3Si.+ N2O, and F3Ge.+ N2O. The latter three systems served as molecular models for experimentally found systems. Based on experimental and theoretical data, the product of N2O addition to (Si–O)3Si.has the structure Si–N=N–O.. The reactions of free radicals H., H3C., H3Si., F2HSi., F3Si., (Si–O)3Si., and (Ge–O)3Ge.with N2O are compared. The spectrum of optical absorbance of the (Si–O)3Si–O.radical is recorded and qualitatively characterized.  相似文献   

4.
1-Ethylpiperazinediium pentachloroantimonate (III) monohydrate, C6H16N2SbCl5·H2O, has been synthesized by the reaction of antimony trioxide (Sb2O3) and 1-ethylpiperazine in an aqueous solution of hydrochloric acid. The structure crystallizes in orthorhombic system, in the non-centrosymmetric space group Pca21 and consists of isolated [C6H16N2]2+ cations, square pyramidal [SbCl5]2− anions and lattice water molecules. OH⋯Cl hydrogen bonds link the [SbCl5]2− anions and water molecules to form double chains stretching along the [101] direction. The chains in turn are linked to the organic cations via NH⋯Cl, CH⋯Cl, CH⋯O and NH⋯O hydrogen bonds to form a three-dimensional network. This structure presents an example of a general square pyramidal complex ion containing a stereo-chemically active lone pair of electrons. Solid state 13C and 15N CP-MAS NMR spectra are in agreement with the X-ray structure, and vibrational absorption bands were identified by infrared spectroscopy. DFT calculations allowed the attribution of the NMR peaks and IR absorption bands. The interactions variability of the two independent cations and ten chloride atoms is analyzed via Hirshfeld surface analysis.  相似文献   

5.
The syntheses and crystal structures of two one-dimensional coordination polymers, [Mn(C5HO2F6)2(C16H20N2)] n (1) and [Mn(C5HO2F6)2(C20H20N2)] n (2), are described, where C5HO2F6 ? is the hexafluoro acetylacetonate anion, C16H20N2 is 1,6-bis(4-pyridyl)-hexane, and C20H20N2 is 1,4-bis[2-(3-pyridyl)ethyl]-benzene. In both phases, the metal ion lies on a crystallographic twofold axis and is coordinated by two chelating C5HO2F6 ? anions and two bridging bipyridyl ligands to generate a cis-MnN2O4 octahedron. The bridging ligands, which are completed by crystallographic inversion symmetry in both compounds, connect the metal nodes into zigzag [20 1 ] chains in 1 and contorted [001] chains in 2. Intrachain C–H???O interactions occur in 1 but not in 2, which may be correlated with the relative orientations of the ligands. Crystal data: 1, C26H22F12MnN2O4, M r = 709.40, monoclinic, C2/c (No. 15), a = 9.3475(2) Å, b = 16.6547(3) Å, c = 18.3649(4) Å, β = 91.1135(8)°, V = 2858.50(10) Å3, Z = 4, R(F) = 0.030, w R(F 2) = 0.075. 2, C30H22F12MnN2O4, M r = 757.44, monoclinic, C2/c (No. 15), a = 19.9198(2) Å, b = 10.6459(2) Å, c = 16.8185(3) Å, β = 119.8344(8)°, V = 3093.91(9) Å3, Z = 4, R(F) = 0.032, w R(F 2) = 0.078.  相似文献   

6.
Reaction of gem-diphenyltetrafluorophosphazene, [1,1-(C6H5)2]P3N3F4 (1) with LiO(CH2)3OLi resulted in the formation of four products, spiro-{3,3-[O(CH2)3O]}[1,1-(C6H5)2]P3N3F2 (2), ansa-{3,5-[O(CH2)3O]}[1,1-(C6H5)2P3N3F2] (3), bridged-[1,1-(C6H5)2N3P3F3][O(CH2)3O][1,1-(C6H5)2N3P3F3] (4) and dangling-[HO(CH2)3O][1,1-(C6H5)2P3N3F3] (5) derivatives of 1, among which compound 5 was found to be the major product. Reaction of 1 with the dilithiated ferrocene derived diol, FcCH2P(S)(CH2OLi)2 resulted in the formation of two isomers of ansa substituted fluorophosphazenes namely endo-[1,1-(C6H5)2]{3,5-[FcCH2P(S)(CH2O)2]}P3N3F2 (6) and exo-[1,1-(C6H5)2]{3,5-[FcCH2P(S)(CH2O)2]}P3N3F2 (7). These were formed along with the spiro isomer [1,1-(C6H5)2]{3,3-[FcCH2P(S)(CH2O)2]}P3N3F2 (8) the dangling derivative [1,1-(C6H5)2P3N3F3][OCH2(FcCH2)P(S)CH2OH] (9) and the bridged compound [1,1-(C6H5)2P3N3F3][OCH2(FcCH2)P(S)CH2O][1,1-(C6H5)2P3N3F3] (10). All compounds were separated by column chromatography and characterized by 1H, 31P{1H}, 19F NMR, mass spectra and elemental analysis. The spirocyclic compound 8 was also characterized by X-ray crystallography.  相似文献   

7.
Imidazole base was crystallized with different aromatic carboxylic acids 2,4-dihydroxybenzoic acid, 5-chlorosalicylic acid, and 1,8-naphthalic acid, affording three new binary molecular organic salts of [(C 3 H 5 N 2 + )·(C 7 H 5 O 4 )] (1), [(C 3 H 5 N 2 + )·(C 7 H 4 O 3 Cl )] C 7 H 5 O 3 Cl (2), and [(C 3 H 5 N 2 + ) (C 12 H 7 O 4 )] (3). Proton transfer occurs from the COOH of carboxylic acid to nitrogen of imidazole in all complexes (1-3), leading to the hydrogen bond N-H…O in all structures. To our knowledge, the recognition pattern between the carboxylic acid group and imidazole (acid-imidazole synthon) is less well-studied so far. The cooperation among COOH, COO and imidazolium cation functional groups for the observed hydrogen bond synthons is examined in the three structures. Generally, the strong N-H…O and O-H…O hydrogen bonds define supramolecular architecture and connectivity within chains, while weaker C-H…O hydrogen bonds play the dominant role in controlling the interactions between layers in these novel organic salts. Thermal stability of these compounds has been investigated by thermogravimetric analysis (TGA) of mass loss.  相似文献   

8.
The initial stage of adsorption of water vapors on active carbons is due to the reaction of the water molecules with inorganic and organic polar sites. For the lowest degrees of filling, the heats of adsorption of H2O on active carbons evacuated at 500°C are overestimated due to the strong physical and chemical reaction with the primary active sites. Adsorption on secondary active sites (second coordination sphere of the active site) results in the formation of aqueous clusters with stressed hydrogen bonds and with heats below the heat of vapor condensation (). Filling of micropores containing water clusters and capillary condensation in mesopores simultaneously take place in the middle region and in the region of saturation. Micropores containing no water clusters do not fill with water even for P/Ps=1. In this region, q > by 3%. Desorption of water from the micropores is almost totally controlled by capillary evaporation of the liquid from the mesopores, and the sorption volume distribution curve by Kelvin radii reflects the distribution of the total volume of meso- and micropores by the radii of the cylindrical mesopores.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2183–2186, October, 1989.  相似文献   

9.
Clathrate Hydrates of Tetrabutylammonium and Tetraisoamylammonium Halides   总被引:3,自引:0,他引:3  
Clathrate formation was considered for two series of systems: (C4H9)4NG–H2O and iC5H11)4NG–H2O G = F-, Cl-, Br-, I-). Clathrate hydrates of tetraisoamylammonium halides were shown to melt at higher temperatures than those of the butyl series. In passing from fluoride to bromide, the stability of compounds of the butyl series falls significantly and tetrabutylammonium iodide does not produce polyhydrates. In the isoamyl series, the melting points of polyhydrates vary insignificantly for different halides. In addition, the highest melting hydrate of tetraisoamylammonium bromide melts at a slightly higher temperature than chloride hydrates, indicating not only a hydrophilic effect of the anion on clathrate formation.  相似文献   

10.
The present work aims chiefly to study the thermal behaviour of complex compounds with general formula: [M(HL)xH2O](A)yH2O (where HL=C13H11N4O2=6-(2-pyridylazo)-3-acetamidophenol (PAAP), M=Cu(II), Zn(II), Cd(II) and Fe(III) x=1, 3; y=2, 5) while A=CH3COO (Ac), Cl2. The second formula is [M(H2L)xH2O]Cl2yH2O, (where H 2 L=C13H12N4O2 (PAAP), M=Ni(II), Co(II) x=3; y=4, 6). The compounds were identified by elemental analysis, FT-IR spectra and TG/DTG,DTA methods. It was found that during the thermal decomposition of complex compounds water molecules of crystallization are released in the first step. In the next step the pyrolysis of organic ligand takes place. Metal oxide remained as a solid product of the thermal decomposition. Mass spectroscopy has been used for the determination of the thermal decomposition on the intermediate products. It was found that the thermal stability of the studied compounds increases as the ionic radii decreases. The activation energy E, the entropy change S *, the enthalpy H * change and Gibbs free energy change G * were calculated from TG curve.This revised version was published online in November 2005 with corrections to the Cover Date.  相似文献   

11.
Potassium peroxypentafluorotantalate monohydrate K2TaO2F5 · H2O was synthesized by the introduction of hydrogen peroxide and potassium chloride into highly pure tantalum-containing fluoride solutions at 70°C followed by cooling of the mixture to room temperature at a rate of 10–15 K/h. The X-ray diffraction analysis revealed that K2TaO2F5 · H2O crystallized in the monoclinic crystal system with the following unit cell parameters: a = 8.965(2) Å, b = 8.966(2) Å, c = 9.257(2) Å, β = 99.78(3) °, Z = 4, V unit cell = 733.3(5) Å3, ρcalcd = 3.681 g/cm3, FW = 404.13, space group C 2 3 = C2(5). The thermolysis of K2TaO2F5 · H2O was studied at 160–1000°C, and the phases formed under specified conditions were determined.  相似文献   

12.
Complexes Ln(Phen)(C6F5COO)3 (Ln = Tb, Eu; Phen = 1,10-phenanthroline) (I, II) are synthesized. At 300 K these complexes and compounds Ln(C6F5COO)3 · nH2O (Ln = Tb, n = 2; Ln = Eu, n = 1) (III, VI) possess photoluminescence (bright in the case of I and II). In the spectrum of compound I the line at 545 nm (transition 5 D 47 F 5) is most intense, whereas in the spectrum of compound II the most intense is the line at 613 nm (transition 5 D 07 F 2). The replacement of Phen by water decreases the luminescence intensity. The compound [Tb2(H2O)8(C6F5COO)6] · 2C6F5COOH (IV) is synthesized. According to the X-ray diffraction data, in structure IV the molecules of the binuclear Tb(III) complex with the C6F5COOH molecules form a supramolecular ensemble due to hydrogen bonding. The C6F5COO? ligands perform the monodentate and bidentate bridging function, resulting in the opening of the eight-membered cycle Tb2C2O4. The TbO8 polyhedron is a distored tetragonal antiprism. The crystals of the binuclear complex [Tb2(H2O)8(C6F5COO)6] (V) are obtained in which the C6F5COO? ligands are monodentate and tridentate bridging cyclic, which results in the closure of two four-membered cycles TbO2C and one four-membered cycle Tb2O2. The TbO9 polyhedron is a distorted monocapped tetragonal antiprism.  相似文献   

13.
Three clathrate hydrates: (i-C5H11)2·(C4H9)2NCl·38H2O (mp 20.5°C), (i-C5H11)2·(C4H9)2NCl·32H2O (mp 22.2°C), and (i-C5H11)2·(C4H9)2NCl·27H2O (mp 23.8°C) were detected in the system diisopentyldibutylammonium chloride-water. Crystals of all the compounds were isolated, and their composition was determined. The size effect of the halide anions (F?, Cl?, and Br?) on the properties of related compounds was considered.  相似文献   

14.
Two different hydrogen-bonded inclusion compounds, [2,4,6-C5H2N(COO?)3]0.5·[C(NH2) 3 + ]0.5·[(C2H5)4N+]·2H2O (1) and [2,4,6-C5H2N(COO?)3]·[C(NH2) 3 + ]·[(C2H5)4N+]·[(C3H7)4N+]·6H2O (2) are reported in this paper, in which 2,4,6-pyridine-tricarboxylic anions, guanidiniums and water molecules jointly construct host lattices while tetraalkylammonium cations are accommodated as guest species. Both two compounds formed sandwich-like hydrogen-bond inclusion compounds. In compound 1, the dimers composed of 2,4,6-pyridine-tricarboxylic anions and guanidiniums form 2D hydrogen-bonded layers by connecting with water molecules. In compound 2, 2,4,6-pyridine-tricarboxylic anions, guanidiniums and water molecules contribute to generate an undulate rosette hydrogen-bonded architecture. Interestingly, in compound 2, there are two species of guest molecules, tetraethylammonium and tetrapropylammonium, which are alternately arranged between the neighboring layers. Mixed guest cations accommodated in hydrogen-bonded inclusion compounds are seldom seen.  相似文献   

15.
The preparation of a number of new 9-substituted octafluorofluorene derivatives, solution NMR studies, and the first examples of solid state structures of octafluorofluorenes [1,2,3,4,5,6,7,8-octafluorofluorene, C13H2F8, 1; 1,2,3,4,5,6,7,8-octafluoro-9-(pentafluoro)phenylfluorene, C19HF13, 8; 1,1′,2,2′,3,3′,4,4′,5,5′,6,6′,7,7′,8,8′-hexadecafluoro-9,9′-bifluorenyl, C26H2F16, 11] are reported. Variable temperature 19F NMR investigations have been performed on the 9-aryl substituted compounds 1,2,3,4,5,6,7,8-octafluoro-9-(pentafluoro)phenyl-9-hydroxyfluorene, C19HF13O, 4, 1,2,3,4,5,6,7,8-octafluoro-9-(nonafluoro-4′-biphenylyl)-9-hydroxyfluorene, C25HF17O, 5, and 8, and the energetic barriers to rotation of the aryl have been determined. A lower rotational barrier is observed for compound 4 with respect to compound 8, while 5 does not show fluxional behaviour below 338 K. The results of the variable temperature experiments performed on 8 have been rationalized by 2D NMR studies, and compared to the solid state data resulting from the X-ray structural analysis.  相似文献   

16.
An organically templated yttrium fluoride has been prepared hydrothermally and characterised by X-ray powder diffraction. The crystal structure of [C3N2H12]0.5[Y3F10] may be regarded as a ‘Super-Diamond’ framework, space group Fd, a=15.4817(1) Å, where each carbon atom site of the diamond structure is replaced by a polyhedral [Y6F8F24/2]2− unit. The basic framework type is isostructural with the known phase (H3O)[Yb3F10]·H2O. The novelty in the present case lies in the use of the organic structure-directing agent 1,3-diaminopropane.  相似文献   

17.
Hydrogen/deuterium (H/D) exchange reactions of fluorophenyl and difluorophenyl anions (C6H4F?, o-C6H3F 2 ? , m-C6H3F 2 ? , p-C6H3F 2 ? ) have been studied using the flowing afterglow-selected ion flow tube technique. The C6H4F? anion exchanges all hydrogens for deuterium upon reaction with D2O. The difluorophenyl anions o-, m-, and p-C6H3F 2 ? exchange three, two, and one hydrogen, respectively, with D2O, whereas they undergo one, two, and three H/D exchanges, respectively, with CH3OD. The structures of the anions and the isotope exchange dynamics within the intermediate ion-dipole complexes are discussed using ab initio molecular orbital calculations. Calculated values for the proton affinities of the most stable anions are 385.2, 378.0, 371.9, and 378.2 kcal/mol for C6H4F?, o-C6H3F 2 ? , m-C6H3F 2 ? , and p-C6H3F 2 ? , respectively, in excellent agreement (within 2 kcal/mol) with the previous experimental values for the acidities of the corresponding fluorobenzenes. The H/D exchange results are explained by the energy differences of the intermediate DO? and CH3O? species within the ion-dipole complexes; CH3O? is mobile within the “hot” intermediate complex, whereas DO? is nearly “frozen” within the complex and cannot migrate across the barriers caused by the fluorine atoms or by the π electrons.  相似文献   

18.
Rod-like organogold(I) complexes [AuR(CNC6H4O(O)CC6H4OC10H21-p)] were prepared and their liquid crystal behaviour was studied. Depending on the nature of R, the synthetic methodology was different. Thus, for R = substituted alkynyl ligands, the new compounds were prepared in two steps:(i) reaction of [AuCl(tht)] (tht = tetrahydrothiophene) with R′CCH(R′ = C5H4N, C6H4CN, C6H4CCC5H4N) in the presence of NaOAc to give insoluble [Au(CCR′)]n; (ii) reaction of the latter polymers with the isonitrile CNC6H4O(O)CC6H4OC10H21-p.For R = fluorinated aryls, the complexes were prepared by displacement of tht from the compounds [AuR(tht)] (R = C5F4N, C6F4C5H4N, C6F5) with isonitrile.In addition, an unexpected ionic derivative [Au(CCC5H4NC10H21)2][Au(CCC5H4N)2] was formed in the reaction between [PPh4][Au(CCC5H4N)2] and C10H21I. All these compounds have been characterized by IR and NMR spectroscopy and mass spectrometry. The X-ray crystal structure of the compound with R = CCC5H4N shows a linear molecule in which the gold atom is surrounded by the pyridine-containing acetylene and the isonitrile ligand, and no direct gold-gold interaction occurs. Six of the neutral compounds are liquid crystals and their optical, thermal and thermodynamic data were analyzed and compared in terms of molecular polarizability.  相似文献   

19.
Zusammenfassung Spuren an Fluorid können aus wäßrigen Lösungen mit (C2H5)3SiCl in m-Xylol oder mit (C6H5)4SbOH in CH2Cl2 ausgeschüttelt werden. Von verschiedenen untersuchten Mitfällungsreaktionen erwies sich die Adsorption an Hydroxylapatit als am günstigsten.Durch Gas-Chromatographie mit Flammenionisationsdetektor können noch 0,05 g F/ml m-Xylol als (C2H5)3SiF bestimmt werden. Wegen der normalerweise auftretenden schwankenden Blindwerte von etwa 0,5–1,5 g F lassen sich jedoch Mengen von weniger als ca. 3 g F in der Regel nicht mehr bestimmen.
Separation and gas-chromatographic determination of traces of fluoride
Traces of fluoride can be separated from aqueous solution by extraction with (C2H5)3SiCl in m-xylene or with (C6H6)4SbOH in CH2Cl2. Furthermore, several coprecipitation reactions were tested; adsorption on hydroxyl apatite is most suitable.Determination of 0.05 g F/ml can be performed by gas chromatography of (C2H5)3SiF in m-xylene using flame ionisation detectors; but variable blanks of 0.5–1.5 g F normally prevent the determination of less than ca. 3 g F.
  相似文献   

20.
The magnesium sulphate complex compounds of general formulae [Mg(H2O)6]2+·2(C6H12N4)·SO4 2?·5(H2O) (1) and Mg(C12H8N2)(H2O)3SO4 (2) have been synthesized, characterised by elemental and thermal analysis, IR, UV?CVIS and fluorescence spectroscopy, and X-ray crystallography. The obtained compounds are air stable at room temperature and well soluble in water. In the structures of the investigated complex compounds the O?CH?O, O?CH?N, and C?CH?O hydrogen bonds exist, and they create N2C 2 2 (8), R 2 2 (8) (compound 1) and N1C 1 1 (6), N1R 2 2 (12) (compound 2) patterns. Their thermal decomposition processes in the investigated atmospheres (air and helium) are different. After the slightly similar dehydratation, the observed transitions and the obtained final products are different (in helium atmosphere the sulphate ion of studied compounds undergoes decomposing what does not take place in air atmosphere). The UV?CVIS spectrum of 2 shows maxima that are typical for ????????* and n??????* transitions, and fluorescence spectrum of the same compound displays its great fluoresce properties. The 1 does not exhibit absorption in the investigated region of electromagnetic spectrum due to the absence of respect chromophore groups. The IR spectrum of 2 shows typical vibrations for chelating amine molecule. An interesting fact is that in 1 the SO stretching vibrations (existing at 1119 and 1182?cm?1) are doubled in comparison to the magnesium sulphate whilst in 2 these vibrations are absent.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号