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1.
The IR spectra of alkaline and alkaline earth metal perchlorate and of lithium bromide solutions in acetonitrile, obtained with the help of FTIR measurements in the region of the C-N stretching mode of the solvent, reveal bands produced by acetonitrile molecules in the solvation shells and bands of ClO 4 ions in contact and solvent separated ion pairs. The shift and the attenuation of the C-N stretching band of acetonitrile at 2254 cm–1 is used for the calculation of cation solvation numbers for Li+(4), Na+(4), Mg2+(6), Ca2+(6), and Ba2+(6). No solvation is assumed for the contact ion pairs of LiClO4, LiBr, NaClO4, Mg(ClO4)2, Ca(ClO4)2, and Ba(ClO4)2. The association constants of the symmetrical electrolytes are compared to those obtained from other methods.  相似文献   

2.
Chemical states of tritium existing in neutron-irradiated solid lithium compounds were analyzed using a radiometric method. Nearly 100% of tritium was found in the T+ state in LiOH, Li2O2 and Li3N, while the T state predominated in LiH, Li7Pb2 and Li2C2. Tritium incorporated in Li2O, Li2S, LiF, LiCl, LiBr and LiI was distributed over the T+, T and T0 states. In Li2O crystals, the distribution of tritium in the T+ state increased from 58% to 81% with increasing neutron fluence from 2.5×1016 cm–2 to 6.3×1017 cm–2.  相似文献   

3.
Raman and infrared spectra of polycrystalline6Li2C2O4 and7Li2C2O4 have been investigated in the wavenumber region from 1,800 to 40 cm–1. The internal C2O4 –2 vibrations have been studied on the basis of a D2h molecular structure and the correlation field splittings have been found to be about 40 cm–1 for the stretching modes and about 15 cm–1 for the bending modes. The external vibrations of the Li+ and C2O4 –2 sites have been discussed by considering the results of the factor group analysis and the6Li/7Li isotope effect on the normal vibrations.
Raman- und Infrarot-Spektren von6Li2C2O4 und7Li2C2O4
Zusammenfassung Es wurdenRaman- und IR-Spektren von polykristallinem6Li2C2O4 und7Li2C2O4 im Bereich der Wellenzahlen von 1800 bis 40 cm–1 untersucht. Die internen Schwingungen wurden auf der Basis einer D2h Molekülstruktur analysiert. Für die Streckschwingungen wurde eine Korrelationsaufspaltung von etwa 40 cm–1 gefunden, für die Deformationsschwingungen etwa 15 cm–1. Die Diskussion der externen Schwingungen von Li+ und C2O4 –2 erfolgte unter Berücksichtigung der Resultate der Faktorgruppenanalyse und des6Li/7Li Isotopeneffekts auf die Normalschwingungen.
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4.
The vibrational spectra of LiPF6 1M solutions formed in aprotic mixed solventsobtained by mixing ethylene carbonate with dimethyl carbonate and diethylcarbonate are discussed. The Raman and infrared spectra of lithium hexafluorophosphate(LiPF6) and the quantum chemical computations of the vibrationalwavenumbers and intensities are reported. Due to the nature of the solutions,attenuated total internal reflectance spectroscopy was used to obtain the infraredspectra. The infrared active vibrational fundamentals of PF6 provided evidencefor the anion—solvent interaction as well as ion-pair formation. Similarly, theinfrared active modes of the solvent showed significant changes due to thecation—solvent interaction. The computations of the most energetically favorablegeometry in the formation of the Li+ PF6 ion pair are also presented. Conductivitymeasurements carried out for the 1M solutions scanning a wide temperatureinterval (–30 to + 60 °C) confirm the viability of these electrolytes forpractical applications.  相似文献   

5.
IR spectra of 3 normal solutions of 14 different salts [chlorides of Al+++, Be++, Mg++, Ca++, Sr++, Ba++, Zn++, Cd++, Li+, Na+, K+, Rb+, Cs+, N(CH3) 4 + ] in both, 96% H2O+4% D2O and 100% H2O, were measured in the frequency range =2 800–2 100 cm–1. From up to 18 single measurements for each solution the frequencies and halfwidths of the O-D stretching bands of isotopically dilute HDO were determined with high accuracy. Frequencies in the range =2 510–2 529 cm–1 and halfwidths in the range =155–205 cm–1 resulted atT=30°C with standard deviations typical less than ±1 cm–1 and ±4 cm–1, respectively. An almost perfect correlation between the O-D stretching band parameters and the polarizing power of the cations was obtained.Herrn Prof. Dr.A. Neckel, Wien, zum 60. Geburtstag gewidmet.  相似文献   

6.
The high resolution Fourier transform infrared spectra of thev 4-v 2 andv 7 band systems of tricarbon disulfide, SCCCS, were measured with a Bomem D A3.002 interferometer and an apodized resolution of 0.004 cm–1. The rotational structure of the bandsv 4-v 2, (v 4+v 7)–(v 2+v 7), (v 4+2v 7)–(v 2+2v 7) andv 7 could be resolved and assigned. The analysis confirmed that SCCCS displays the dynamics of a linear molecule.  相似文献   

7.
Solvation and association interactions in solutions of LiBF4/DMCC (DMCC for N,N-dimethylcarbamoyl chloride) and LiBF4/DMCC–DME (DME for 1,2-dimethoxyethane) have been studied as a function of concentration of lithium tetrafluoroborate by infrared and Raman spectroscopy. Strong interactions between Li+ and solvent molecules or BF4 anions are observed. The apparent solvation numbers of Li+ in LiBF4/DMCC solutions were deduced. Band-fitting to the B–F stretching band of BF4 anion permits detailed assess of the ion pairing. Based on the calculations of density function theory, optimal structures of Li+(DMCC)n (n = 1–3) were suggested. It is found that the lithium ion was preferentially solvated by DME in DMCC–DME binary solvents. This finding is supported by quantum chemistry calculations.  相似文献   

8.
For lithium halides, LiX (X = Cl, Br and I), hydrates with a water content of 1, 2, 3 and 5 moles of water per formula unit are known as phases in aqueous solid–liquid equilibria. The crystal structures of the monohydrates of LiCl and LiBr are known, but no crystal structures have been reported so far for the higher hydrates, apart from LiI·3H2O. In this study, the crystal structures of the di‐ and trihydrates of lithium chloride, lithium bromide and lithium iodide, and the pentahydrates of lithium chloride and lithium bromide have been determined. In each hydrate, the lithium cation is coordinated octahedrally. The dihydrates crystallize in the NaCl·2H2O or NaI·2H2O type structure. Surprisingly, in the tri‐ and pentahydrates of LiCl and LiBr, one water molecule per Li+ ion remains uncoordinated. For LiI·3H2O, the LiClO4·3H2O structure type was confirmed and the H‐atom positions have been fixed. The hydrogen‐bond networks in the various structures are discussed in detail. Contrary to the monohydrates, the structures of the higher hydrates show no disorder.  相似文献   

9.
The negative ion photoelectron spectrum of7Li 2 is reported at 488 nm (2.540 eV). Three electronic bands are observed in this spectrum and are assigned to the following photodetachment transitions:7Li2,X 1 g + +e 7Li 2 ,X 2 u + ;7Li2,a 3 u + +e 7Li 2 ,X 2 u + ; and7Li2,A 1 u + +e 7Li 2 ,X 2 u + . The electron affinity of7Li2 is determined to be 0.437±0.009 eV, leading to an anion dissociation energy,D 0, of 0.865±0.022 eV for the ground state of7Li 2 . A Franck-Condon analysis of the7Li2,X 1 g + +e 7Li 2 ,X 2 u + band yields the following spectroscopic constants for the ground state of7Li 2 :B e =0.502±0.005 cm–1,r e =3.094±0.015 Å, and e =232±35 cm–1.  相似文献   

10.
The thermal behaviour of complexes [Li+-EC](AlH4) withEC=12-C-4, 15-C-5, DC 18-C-6 (cis-anti-cis andcis-syn-cis isomers) was investigated by Differential Scanning Calorimetry (DSC). These complexes were prepared as solids from benzene solutions. Pure EC and several solvated species [Li+-EC](AlH4)·nC6H6 (EC=15-C-5, DC 18-C-6syn) were also studied. DSC has revealed various phenomena. Solid-solid transitions were observed before melting for [Li+-EC](AlH4) withEC=12-C-4 and 15-C-5. They are probably explained by small molecular modifications strongly dependent on the thermal history of the sample. A glass-transition was found for the pure crown-ether DC 18-C-6anti, the complex [Li+-EC](A1H4) withEC=DC-18-C-6anti and the two solvates mentioned above.
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11.
Infrared spectra in digitized form were measured for NaNO3 and [Na·C221]+NO 3 solutions in DMSO-d6 between 1150 and 1500 cm–1 using a technique and instrumentation that obtains each point of the average absorbance spectrum at the same (reduced) noise level. Similar spectra were also obtained for the solvent and the Na+ complexed cryptand C221 and used to remove the contribution of these entities from the above spectra. By taking appropriate differences of spectra, it was possible to reveal both bands of the contact ion pair in the NaNO3/DMSO-d6 solution-removing one from under the strong band of the D3h site—and to show the presence of three ion sites in this solution. The third site is tentatively identified as a close ion pair. Two ion sites are also identified in the [Na·C221]+NO 3 /DMSO-d6 solution.Paper X in the series, Studies of Solution Character, by Molecular Spectroscopy.  相似文献   

12.
Raman spectra of aqueous Zn(II)–perchlorate solutions were measured over broad concentration (0.50–3.54 mol-L–1) and temperature (25–120°C) ranges. The weak polarized band at 390 cm–1 and two depolarized modes at 270 and 214 cm–1 have been assigned to 1(a 1g), 2(e g), and 5(f 2g) of the zinc–hexaaqua ion. The infrared-active mode at 365 cm–1 has been assigned to 3(f 1u). The vibrational analysis of the species [Zn(OH2) 2 + ] was done on the basis of O h symmetry (OH2 as point mass). The polarized mode 1(a 1g)-ZnO6 has been followed over the full temperature range and band parameters (band maximum, full width at half height, and intensity) have been examined. The position of the 1(a 1g)-ZnO6 mode shifts only about 4 cm–1 to lower frequencies and broadens by about 32 cm–1 for a 95°C temperature increase. The Raman spectroscopic data suggest that the hexaaqua–Zn(II) ion is thermodynamically stable in perchlorate solution over the temperature and concentration range measured. These findings are in contrast to ZnSO4 solutions, recently measured by one of us, where sulfate replaces a water molecule of the first hydration sphere. Ab initio geometry optimizations and frequency calculations of [Zn(OH2) 2 + ] were carried out at the Hartree–Fock and second-order Møller–Plesset levels of theory, using various basis sets up to 6-31 + G*. The global minimum structure of the hexaaqua–Zn(II) species corresponds with symmetry T h. The unscaled vibrational frequencies of the [Zn(OH2) 2 + ] are reported. The unscaled vibrational frequencies of the ZnO6, unit are lower than the experimental frequencies (ca. 15%), but scaling the frequencies reproduces the measured frequencies. The theoretical binding enthalpy for [Zn(OH2) 2 + ] was calculated and accounts for ca. 66% of the experimental single-ion hydration enthalpy for Zn(II).Ab initio geometry optimizations and frequency calculations are also reported for a [Zn(OH2) 2 18 ] (Zn[6 + 12]) cluster with 6 water molecules in the first sphere and 12 in the second sphere. The global minimum corresponds with T symmetry. Calculated frequencies of the zinc [6 + 12] cluster correspond well with the observed frequencies in solution. The 1-ZnO6 (unscaled) mode occurs at 388 cm–1 almost in perfect correspondence to the experimental value. The theoretical binding enthalpy for [Zn(OH2) 2 18 ] was calculated and is very close to the experimental single ion-hydration enthalpy for Zn(II). The water molecules of the first sphere form strong hydrogen bonds with water molecules in the second hydration shell because of the strong polarizing effect of the Zn(II) ion. The importance of the second hydration sphere is discussed.  相似文献   

13.
Summary The complexes M(acac)2(imidazole)2 (M = Co or NO and [M(acac)2B]n (M = Co, Ni or Zn; B = pyrazine or pyrimidine) have been prepared and their i.r. spectra determined over the 600–140 cm–1. range. The metal-oxygen and metal-nitrogen stretching frequencies, (M-O) and v(M-N), are assigned on the basis of the band shifts induced by deuteriation of the adducted base and by substitution of the metal ion. Three or fourv(M-O) bands are observed within the 600-200 cm–1 range. The twov(M-O) bands of higher frequency are considered to the coupled with internal ligand modes. TwovM-N) bands are observed within the 280–170 cm–1. range. The metal-ligand stretching frequencies are in good agreement with the values previously established for these vibrations in the [M(imidazole)6]2+ and Ni(acac)2(pyridine)2 complexes.  相似文献   

14.
The Raman spectra of N2O4 solutions in organic solvents have been recorded. The frequencies ofv 1,v 2, andv 3 bands of N2O4 increase with increasing solvent electron-donor properties. Especially large changes ofv 3 N-N stretching band have been observed (254.5 cm–1 in n-hexane, 276.5 cm–1 in 1,4-dioxane). The ab initio calculations have shown that the interaction between N2O4 and electron-donor molecules causes an increase of N-N and N-O stretching and O-N-O bending force constants of N2O4 in agreement with the results of Raman study.  相似文献   

15.
The variations in the structure of deep-level calcinated NH4Na-Y zeolite (68 % NH4 +, Si/Al = 2.56) at 873 K (stage I of the hydrothermal dealumination) as a result of ammonation and subsequent calcination in water vapor at 973 and 1023 K (stageII) were studied using the IR spectra of zeolite framework vibrations. It was shown that ammonation of the product of stageI promotes the formation of linear disiloxane bonds and extra-framework =AlVI-OH species identified by absorption at 482, 1196 cm–1, and 524, 612, 829 cm–1. The ammonation is also accompanied by an increase in the excessive negative framework charge (ENFC), which is manifested in the high-frequency (HF) shift of the bands that have maxima in thev as (TO4) region and equals 10 cm–1, and also by a decrease in the unit cell parameter (a 0) by 0.14 Å. The decrease in both the ENFC anda 0 for the products of stageII, v as (TO4) = 10–20 cm–1 and a 0 = 0.07–0.14 Å, is due to the formation of nonlinear disiloxane bonds and non-framework aluminum hydroxide species identified by the absorption bands at 478, 1173 cm–1 and 530, 615, 835 cm–1.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 660–664, April, 1993.  相似文献   

16.
This paper reports the results of a variety of experiments carried out for understanding the solvation behavior of potassium thiocyanate in methanol–water mixtures. Electrical conductivity, speed of sound, viscosity, and FT-Raman spectra of potassium thiocyanate solutions in 5 and 10% methanol–water (w/w) mixtures were measured as functions of concentration and temperature. The conductivity and structural relaxation time suggest the ion–solvent and solvent-separated ion–ion associations increase as the salt concentration increases in the mixtures. The Raman band shifts due to the C–O stretching mode of methanol for the solvent mixtures reveal the formation of methanol–water complexes. The significant changes in the Raman bands for the C–N, C–S and O–H stretching modes indicate the presence of SCN−solvent interactions through the N-end, “free” SCN and the solvent-shared ion pairs as potassium thiocyanate is added to the methanol–water mixtures. The relative changes corresponding to H–O–H bending and C–O stretching frequencies indicate that K+ is preferentially solvated by water in these solvent mixtures. The appearance and increase of the intensity of a broad band at ≈940 cm−1 upon salt addition was attributed to the SCN–H2O–K+ solvent-shared ion pairs. No Raman spectral evidence for K+(H2O)n species was observed. The preferential solvation of K+ and SCN in the methanol−water mixtures was verified by the application of the Kirkwood−Buff theory of solutions. This theory confirms that K+ is strongly preferentially solvated by water, whereas SCN is preferentially solvated by the methanol component.  相似文献   

17.
The third Li+ translational mode of lattice vibration of lithium hydrogen oxalate monohydrate has been assigned to the band at about 383/360 cm–1 taking the characteristic6Li/7Li isotope band shifts into consideration.
Über die Zuordnung einer der drei translatorischen Li+-Moden in Lithiumhydrogenoxalat-Monohydrat (Kurze Mitteilung)
Zusammenfassung Es wurden die IR-Spektren der Li- und H-isotopen Lithiumhydrogenoxalat-Monohydrate bei 100 K und 300 K gemessen. Einer der drei translatorischen Moden wird einer Bande zugeordnet, die bei Berücksichtigung der6Li/7Li Isotopenverschiebung bei 383/360 cm–1 auftritt.
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18.
Poly(triazine imide) was synthesized with incorporation of Li+ and Cl? ions (PTI/Li+Cl?) to form a carbon nitride derivative. The synthesis of this material by the temperature‐induced condensation of dicyandiamide was examined both in a eutectic mixture of LiCl–KCl and without KCl. On the basis of X‐ray diffraction measurements of the synthesized materials, we suggest that a stoichiometric amount of LiCl is necessary to obtain the PTI/Li+Cl? phase without requiring the presence of KCl at 873 K. PTI/Li+Cl? with modification by either Pt or CoOx as cocatalyst photocatalytically produced H2 or O2, respectively, from water. The production of H2 or O2 from water indicates that the valence and conduction bands of PTI/Li+Cl? were properly located to achieve overall water splitting. The treatment of PTI/Li+Cl? with [Pt(NH3)4]2+ cations enabled the deposition of Pt through ion exchange, demonstrating photocatalytic activity for H2 evolution, while treatment with [PtCl6]2? anions resulted in no Pt deposition. This was most likely because of the preferential exchange between Li+ ions and [Pt(NH3)4]2+ cations.  相似文献   

19.
Specific sorption sites for nitrogen, N2, in NaLSX and LiLSX zeolites were investigated using a DRIFT spectroscopic method. Sorption of molecular hydrogen, H2, by NaLSX or LiLSX zeolite at 77 K with DRIFT control of perturbation of sorbed molecules allowed to discriminate two or three different types of specific sorption sites in the respective zeolites. Their H–H stretching frequencies are 4077 and 4081 cm–1 for NaLSX, and 4061, 4084 and 4129 cm–1 for LiLSX. With reference to an independent investigation by methods of both sorption thermodynamics and molecular modeling for N2 sorption on LiLSX, the first two of the corresponding bands were ascribed to H2 sorption on lithium cations, Li+, localized in supercages of the faujasite, FAU, zeolite framework at sites SIII and SIII, while the latter band most likely belongs to H2 sorption on Li+ cations at sites SII, and on hydroxyl groups, OH. Sorption of N2 by Li+ cations at sites SIII and SIII is the strongest, resulting in a decrease of intensity of the corresponding DRIFT bands that stem from subsequent H2 sorption. Nitrogen sorption by Li+ cations at sites SII is much weaker. Sorption of N2 on Na+ cations at sites SIII in NaLSX zeolite is also stronger than by Na+ cations at sites SII.  相似文献   

20.
The new lithium-selective complexant 5,12,17-trimethyl-1,5,9,12,17-pentaazabicyclo[7.5.5]nonadecane (TMPAND) was used to synthesize Li+(TMPAND)Na–, the first alkalide prepared from an azacage complexant. This sodide was characterized by a variety of methods. Differential scanning calorimetry experiments showed a reversible, endothermic, solid-solid phase transition at an onset temperature of –75 ± 3°C and with H = 3.3 ± 1 kJ/mol.23Na NMR spectra showed a peak at –61 ppm, characteristic of a sodium anion, and a second minor peak at –10 ppm, probably due to the interaction of Na- with trapped electrons. The quadrupole coupling constant of the complexed lithium cation was found to be 0.19 MHz at –100°C, and7Li NMR spectra showed a discontinuity in the line width of the7Li NMR peak and in the quadrupole coupling constant at the phase transition.This paper is dedicated to the memory of the late Dr C. J. Pedersen.  相似文献   

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