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  • 1.
    Andersson, Pher
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry. Department of Biochemistry and Organic Chemistry, Organic Chemistry I.
    Bäckvall, Jan-E.
    Palladium-Catalyzed Tandem Cyclization of 4,6- and 5,7-Diene Amides. A New Route towards the Pyrrolizidine and Indolizidine Alkaloids1992In: J. Am. Chem. Soc., Vol. 114, no 22, p. 8696-8698Article in journal (Refereed)
  • 2.
    Berger, R
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry. Oorganisk kemi.
    Önnerud, P
    Tellgren, R
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry. Oorganisk kemi.
    Structure refinements of LiCu2O2 and LiCu3O3 from neutron powder diffraction data1992In: Journal of Alloys and Compounds, Vol. 184, p. 315-322Article in journal (Refereed)
    Abstract [en]

    In its inherent ability to discern light elements in a heavy-atom matrix, neutron powder diffraction has been used at room temperature to confirm structure hypotheses of LiCu2O2 and LiCu3O3, inferred from previous X-ray diffraction studies.

  • 3.
    Berger, Rolf
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry. Oorganisk kemi.
    Bucur, Romulus V.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry. Oorganisk kemi.
    Electrochemistry applied on the TlCu3Se2/TlCu2Se2 phase transformation1992In: Materials Research Bulletin, Vol. 27, p. 439-446Article in journal (Refereed)
    Abstract [en]

    PreviousLy, chemical oxidation of TlCu3X2 (X= S,Se) as a powder immersed in ammonia solution effectuated a phase transformation into the p-metal TlCu2X2. In order to explore whether the small grain size and intimate contact with the liquid phase were imperative, we introduce an electrochemical method with the starting phase as a polished rotating electrode.---The microstructures of polished electrode surfaces indicate that processes within the solid rather than in the interface with the electrolyte are important. The slower and less efficient reduction process may be explained from topotactic symmetry considerations.

  • 4.
    Bergman, Jan
    et al.
    CNT, DEPT ORGAN CHEM, S-14157 HUDDINGE, SWEDEN .
    Lidgren, Göran
    ROYAL INST TECHNOL, DEPT ORGAN CHEM, S-10044 STOCKHOLM 70, SWEDEN.
    Gogoll, Adolf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Organic Chemistry.
    Synthesis and Reactions of Oxazolones from L‑Tryptophan and α‑Haloacetic Anhydrides1992In: Bulletin des Sociétés chimiques belges, ISSN 0037-9646, Vol. 101, no 7, p. 643-660Article in journal (Refereed)
    Abstract [en]

    Optically active 5(4H)-oxazolones have been synthesized from L-tryptophan and an excess of trifluoro-, trichloro-, and dichloroacetic anhydrides. Some of the 5(4H)-xazolones have been further transformed to the isomeric 5(2H)-oxazolones as well as oxazolones with exocyclic double bonds. Treatment of the various oxazolones under hydrolytic, acidic and Friedel-Crafts acylation conditions gave indole-3-pyruvic acid, alpha,beta-dehydrotryptophans, beta-carbolines as well as the functionalized cyclopentanoindole 32. Treatment of the 4-(3-indolylmethyl)-2-trifluoromethyl-5(2H)-oxazolone (17) with trifluoroacetic acid gave the 3,4-bridged azepinoindole 35.

  • 5. Bäckvall, Jan-E.
    et al.
    Andersson, Pher
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry. Department of Biochemistry and Organic Chemistry, Organic Chemistry I.
    Intramolecular Palladium-Catalyzed 1,4-Addition to Conjugated Dienes. Stereoselective Synthesis of Fused Tetrahydrofurans and Tetrahydropyrans1992In: J. Am. Chem. Soc, Vol. 114, no 16, p. 6374-6381Article in journal (Refereed)
  • 6.
    Eriksson, Alf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Analytical Chemistry.
    Carbon Electrodes for Analysis of Organic Compounds with some Applications1992Licentiate thesis, monograph (Other academic)
  • 7.
    HERMANSSON, KERSTI
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry.
    FROM CLUSTER TO CRYSTAL - ABINITIO CALCULATIONS OF THE OH- FREQUENCY IN LITHIUM HYDROXIDE MONOHYDRATE1992In: Chemical Physics, ISSN 0301-0104, E-ISSN 1873-4421, Vol. 159, no 1, p. 67-73Article in journal (Refereed)
    Abstract [en]

    The fundamental O-H stretching frequency of the OH- ion in crystalline LiOH.H2O has been calculated by ab initio methods at the MP2 level. The experimental and calculated wavenumbers are 3575 and 3602 cm-1, respectively. This frequency is shown to result from a delicate balance of several important interactions between the OH- ion and its surroundings: the two cations in the (Li+)2.OH- cluster produce an upshift of 75 cm-1 with respect to the isolated ion, while the whole nearest-neighbour cluster, (Li+)2(H2O)2.OH-.OH-, gives a frequency downshift of -570 cm-1. The crystal field outside the nearest-neighbour cluster produces an upshift of 610 cm-1. This behaviour conforms well with the frequency versus field correlation curves calculated for simple hydroxide point charge complexes.

  • 8.
    Hermansson, Kersti
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry.
    Ojamäe, Lars
    From Molecule to Cluster to Bulk - Water OH Vibrations in Different Surroundings1992In: International Journal of Quantum Chemistry, ISSN 0020-7608, E-ISSN 1097-461X, Vol. 42, no 5, p. 1251-1270Article, review/survey (Refereed)
    Abstract [en]

    Vibrational spectra for the O-H stretching motion of HDO molecules in different surroundings have been calculated by quantum mechanical ab initio methods and compared with experimental spectra. The free water molecule, water chains, and ion-water clusters are discussed. Solvent effects on OH vibrations in liquid water have been calculated as well as "in-crystal" OH frequencies in some ice and ionic crystalline hydrate structures. The importance of nonadditivity effects, electron correlation (at the MP2 level), and long-range interactions for the total frequency downshift is demonstrated. It is shown that the inclusion of these effects, in conjunction with a variational quantum mechanical treatment of the anharmonic vibrational stretching motion (force constants up to the fourth order), yields vibrational frequencies in quantitative agreement with experiment for a wide range of aqueous systems.

  • 9.
    Lindblom, Torbjörn
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry, Analytical Chemistry.
    Irreversible absorption of diphenylamine onto a straight phase and a reversed phase HPLC-column1992In: Symposium on Chemical Problems Connected with the Stability of Explosives, ISSN 0348-7180, Vol. 9, p. 205-213Article in journal (Refereed)
  • 10. OJAMAE, LARS
    et al.
    HERMANSSON, KERSTI
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry.
    THE OH STRETCHING FREQUENCY IN LICLO4-BULLET-3H2O(S) FROM ABINITIO AND MODEL POTENTIAL CALCULATIONS1992In: Chemical Physics, ISSN 0301-0104, E-ISSN 1873-4421, Vol. 161, no 1-2, p. 87-98Article in journal (Refereed)
    Abstract [en]

    The "in-crystal" frequency of the anharmonic and uncoupled OH stretching vibration of HDO molecules in LiClO4.3H2O(s) has been calculated by quantum-mechanical ab initio and model potential methods and compared with the experimental infrared frequency from isotope-isolated HDO molecules. The effects of the nearest neighbours as well as of the crystalline environment have been investigated by the two computational techniques. In both cases, the one-dimensional potential for an anharmonic OH oscillator was constructed from point-wise energy calculations and the Schrodinger equation for the protonic motion in this potential well was solved by a variational procedure. In the ab initio calculations, vibrational potentials were constructed from RHF and MP2 type calculations of point-charge embedded ClO4-.HDO and (Li+)2.(ClO4-)2.HDO clusters using DZP and TZP basis sets. For the LiClO4.3H2O(s) crystal, the ab initio OH frequency is in close quantitative agreement with experiment when electron correlation by MP2 and the crystal field are included: 3537 cm-1 (MP2(TZP)) versus the experimental value of 3556 cm-1. Inclusion of the crystal field is essential and can in this crystal be satisfactorily represented by Ewald field-consistent point charges outside the hydrogen-bonded ClO4-...HDO cluster. In the model potential calculations, analytical intermolecular pair potential functions from the literature were used in conjunction with an experimental intramolecular potential function for the OH stretching motion. The particular intermolecular model chosen here yields an absolute OH frequency 160 cm-1 below experiment. These calculations exemplify some of the difficulties encountered when employing analytical model potentials in vibrational studies.

  • 11. OJAMAE, LARS
    et al.
    HERMANSSON, KERSTI
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry.
    WATER-MOLECULES IN DIFFERENT CRYSTAL SURROUNDINGS - VIBRATIONAL O-H FREQUENCIES FROM ABINITIO CALCULATIONS1992In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 96, no 12, p. 9035-9045Article in journal (Refereed)
    Abstract [en]

    Ab initio quantum-mechanical calculations of anharmonic frequencies for the water O-H vibrations have been performed for a series of crystalline hydrates. In each case, the potential-energy curve for the uncoupled water O-H stretch was derived at the Moller-Plesset MP2 level. Nearest neighbors of the water molecule were explicitly included in the supermolecule and the rest of the surroundings were mimicked by point charges to reproduce the crystal field out to infinity. The time-independent Schrodinger equation for the motion of the proton in this potential well was solved variationally and the frequency was obtained from the energy difference between the 0 and 1 eigenstates. Computed frequencies can be directly compared with existing infrared data for isotope-isolated water molecules in these hydrates. The compounds selected (LiClO4.3H2O, LiHCOO.H2O, LiOH.H2O) exhibit experimental O-H frequency shifts in a wide range, from - 150 down to - 930 cm-1. Good agreement is found between experimental and theoretical frequencies (experimental values in parentheses): 3596 (3556) for LiClO4.3H2O, 3129 (3112) and 3488 (3390) for LiHCOO.H2O, and 2817 (2775) cm-1 for LiOH.H2O. Correlation curves of typical H-bond parameters such as nu(O-H) vs R(H...O), r(e)(O-H) and nu(OH)/nu(OD) have been computed and compared with experiment. The vibrational intensities are also discussed.

  • 12. OJAMAE, LARS
    et al.
    HERMANSSON, KERSTI
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry.
    PROBST, MICHAEL
    THE OH STRETCHING FREQUENCY IN LIQUID WATER SIMULATIONS - THE CLASSICAL ERROR1992In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 191, no 5, p. 500-506Article in journal (Refereed)
    Abstract [en]

    OH stretching frequencies of HDO molecules in liquid water have been calculated by molecular dynamics simulation and compared to quantum-corrected OH stretching frequencies. In the MD simulation the MCY intermolecular water-water potential was used together with an experimental intramolecular free water potential. The frequencies calculated classically by Fourier transformation of the velocity autocorrelation function are found to be almost-equal-to 300 cm-1 too high compared with experiment. Quantum corrections show that the classical error contribution to this discrepancy is almost-equal-to 140 cm-1. To reach full agreement with experiment also the potential model needs to be improved. It is suggested that in constructing flexible water potentials the goal should not be set for an MD-derived OH frequency in absolute agreement with experiment (at 3400 cm-1) but instead some 200 cm-1 higher.

  • 13. OJAMAE, LARS
    et al.
    TEGENFELDT, JÖRGEN
    LINDGREN, JAN
    HERMANSSON, KERSTI
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry.
    SIMULATION OF BAND WIDTHS IN LIQUID WATER SPECTRA - THE BREAKDOWN OF THE FROZEN-FIELD APPROXIMATION1992In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 195, no 1, p. 97-103Article in journal (Refereed)
    Abstract [en]

    Band shapes of liquid water OH vibrational spectra oblained from molecular dynamics (MD) simulation and from a quantum-mechanical method are investigated. The so-called "frozen-field approximation" applied to the calculation of quantum-mechanical high-frequency vibrational spectra is critically examined. It is demonstrated that the band width of the OH stretching spectrum is seriously overestimated through the neglect of the dynamics of the environment in the frozen-field approximation. We show that the proper inclusion of the dynamics in this quantum-mechanical method leads not only to a correct absolute frequency for the model potential used, but also to the correct description of the band width. The basic steps in this method are: (1) an MD simulation yielding an ensemble of liquid water configurations, (2) a quantum-mechanical uncoupled local-mode calculation of the OH frequency for each molecule, using model potentials for the inter- and intra-molecular interactions, (3) inclusion of the influence from the dynamics of the surroundings by filtering out rapid frequency fluctuations. The remaining discrepancy between experimental and computed OH spectra is attributed to shortcomings in the potential model used.

  • 14. Paulsson, Lars-Erik
    et al.
    Lindblom, Torbjörn
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry, Analytical Chemistry.
    Svensson, Lars-Gunnar
    Degradation of Nitro-cellulose. Some Microcalorimetric Studies1992In: Symposium on Chemical Problems Connected with the Stability of Explosives, ISSN 0348-7180, Vol. 9, p. 69-75Article in journal (Refereed)
  • 15. Probst, Michael M.
    et al.
    Hermansson, Kersti
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry.
    ON FREQUENCY-SHIFTS IN OH STRETCHING VIBRATIONS OF HYDRATED CATIONS1992In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 96, no 12, p. 8995-9004Article in journal (Refereed)
    Abstract [en]

    Ab initio calculations of force constants up to fourth order and anharmonic frequencies for the uncoupled O-H stretching vibration in hydrates of the ions Li+, Na+, Mg2+, and Al3+ have been performed at the Hartree-Fock level for M(n+) (H2O)m and M(n+) (H2O)m...(H2O)2 complexes, with m = 5-7. The dependence of force constants and frequency shifts on ion type, cation-water distances, second hydration shell, hydrogen bonding and coordination number is discussed. In the optimized Li+(H2O)6 system, the OH frequency is downshifted 20 cm-1 compared to the free water molecule, whereas, in the optimized Li+ (H2O)6...(H2O)2 complex, the downshift is 120 cm-1. The corresponding numbers for the Al3+ hexaaqua complexes are - 250 and - 1215 cm-1. Frequency shifts with respect to bulk water for the cation-coordinated water molecules have been estimated from the difference between the frequencies of M(n+) (H2O)6...(H2O)2 and a (H2O)2...H2O...(H2O)2 complex. The values are + 85 cm-1 for Li+ and Na+, - 150 cm-1 for Mg2+, and - 1000 cm-1 for Al3+, to be compared with the infrared frequency shifts of + 50 for Li+ and Na+, - 155 for Mg2+ and - 500 cm-1 for Al3+ (experimental aqueous solution values from the literature). The activation energies for water exchange between the hydration shells in the hexaaqua complexes have been calculated for dissociative and associative exchange processes and suggest a dissociative mechanism to be dominant.

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