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  • 1
    Electronic Resource
    Electronic Resource
    Experimental proton affinities for silicon monoxide and silicon monosulfide and their comparison with the proton affinities of carbon monoxide and carbon monosulfide using molecular orbital theory (1989)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 93 (1989), S. 1549-1556 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100341a071
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  • 2
    Electronic Resource
    Electronic Resource
    Theoretical study of the methylsilyl and silylmethyl cations and anions (1981)
    s.l. : American Chemical Society
    The @journal of organic chemistry 46 (1981), S. 998-1003 
    Details
    ISSN: 1520-6904
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/jo00318a029
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  • 3
    Electronic Resource
    Electronic Resource
    Quantum chemical studies on electrophilic addition (1980)
    Springer
    Theoretical chemistry accounts 55 (1980), S. 1-14 
    Details
    ISSN: 1432-2234
    Keywords: 2-aminoethyl cation ; Aziridine, protonated ∼
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The geometries of the 2-aminoethyl cation and the isomeric protonated aziridine have been optimized using ab initio molecular orbital calculations employing the split-valence shell 4-31G basis set. The protonated aziridine is computed to be the more stable ion by 46.5 kcal/mole (4-31G level) and 44.9 kcal/mole (double-zeta basis set). The profile to interconversion is found to have a barrier of less than 15 kcal/mole (relative to the 2-aminoethyl cation) and this profile is compared with those computed for the similar ions XCH2CH 2 + where X=OH, F, SH and Cl.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00551406
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  • 4
    Electronic Resource
    Electronic Resource
    Quantum chemical studies on electrophilic addition (1978)
    Springer
    Theoretical chemistry accounts 47 (1978), S. 97-109 
    Details
    ISSN: 1432-2234
    Keywords: Hydroxonium ion, reaction of ∼ with ethylene ; Epoxides, acid catalysed ring opening of ∼
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The geometries of the 2-hydroxyethyl and isomeric oxiranium cations have been fully optimized using ab initio molecular orbital calculations employing the split valence shell 4-31G basis set. These species are possible intermediates in both the electrophilic addition of OH⊕ to ethylene and in the acid catalysed ring opening of oxirane. The optimized structures were then used to compute more accurate wave functions using Dunning's double-zeta basis set, and with this large basis set the bridged oxiranium ion was found to be the more stable by 7.2 kcal/mole. The barrier to interconversion of these two C2H4OH⊕ ions was computed to be 25.0 kcal/mole above the oxiranium ion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00547747
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  • 5
    Electronic Resource
    Electronic Resource
    Optimum Gaussian basis set for the Bromine atom. Ab initio calculations on the HBr molecule (1975)
    Springer
    Theoretical chemistry accounts 40 (1975), S. 75-80 
    Details
    ISSN: 1432-2234
    Keywords: Bromine, optimized Gaussian basis for ∼ ; HBr
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract An optimum (15 s 12 p 2 d ) Gaussian basis set was obtained for the Bromine atom by minimizing the open shell energy functional. In the minimization procedure the method of conjugate gradients was applied. The optimum (15 s 12 p 2 d ) basis set was contracted to an [8 s 6 p 2 d ] “double zeta” quality basis set and this contracted set was tested on the HBr molecule.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00547915
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  • 6
    Electronic Resource
    Electronic Resource
    A quantum chemical study on electrophilic addition (1975)
    Springer
    Theoretical chemistry accounts 38 (1975), S. 21-35 
    Details
    ISSN: 1432-2234
    Keywords: Fluorine, reaction with ethylene ; Ethylene, reaction of fluorine with ∼ ; Electrophilic addition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Non-empirical SCF-MO calculations were carried out on two limiting structures of C2H4F+, corresponding to the cyclic and open valence tautomers, both of which are possible reaction intermediates of the electrophilic addition reaction of F2 to CH2 =CH2. It was found that both species had thermodynamic stability, corresponding to two distinct minima on the energy surface. However, the 2-fluoroethyl carbonium ion showed a greater stability than the fluoronium ion by about 10 kcal/mole.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01046554
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  • 7
    Electronic Resource
    Electronic Resource
    Quantum chemical studies on electrophilic addition (1977)
    Springer
    Theoretical chemistry accounts 44 (1977), S. 385-398 
    Details
    ISSN: 1432-2234
    Keywords: 2-Chloroethyl and ethylenechloronium cations ; Reaction profile for interconversion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The geometries of the 2-chloroethyl and ethylenechloronium cations, two possible intermediates in the electrophilic addition of chlorine to ethylene, have been fully optimized using ab initio molecular orbital calculations employing the split valence shell 4-31G basis set. These geometries were then used to compute more accurate wave functions using Dunning's double-zeta basis set. The bridged chloronium ion was found to be more stable by 9.35 kcal/mole, the opposite order of stability from the C2H4F+ ions. Interconversion of the two C2H4Cl+ cations was computed to have a barrier of 6.25 kcal/mole. The activation energy for this chlorination reaction, using the ethylenechloronium cation and a chlorine anion at infinite separation as the model for the activated complex, was computed to be 128.7 kcal/mole, showing that this is not a feasible gas phase reaction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00547831
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  • 8
    Electronic Resource
    Electronic Resource
    A theoretical study of C4H5N isomers: Comparison of cyano and isocyano as substituents (1985)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 27 (1985), S. 1-10 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ab initio molecular orbital calculations using a 3-21G basis set have been used to optimize geometries for pyrrole, CH3(X)CCH2, CH3(H)CCHX (both cis and trans), c-C3H5X, and CH2CHCH2X, where X is CN and NC. In all the alkenyl derivatives methyl groups are found to adopt the conformation in which the methyl hydrogen eclipses the double bond. 6-31G*∥3-21G level calculations show the alkenyl cyanides to be of similar energy to pyrrole, but the isocyanides are ∼20 kcal mol-1 higher in energy. For both substituents the cyclopropyl derivatives are higher in energy by ∼10 kcal mol-1. At the 6-31G* level ring strain is 27.7 kcal mol-1 for the cyanide and 30.6 kcal mol-1 for the isocyanide. Data on the relative energies of RCN and RNC are compared when R is (i) a saturated hydrocarbon, (ii) an unsaturated hydrocarbon, (iii) an α-carbenium ion, (iv) an allyl cation, and (v) an α-carbanion.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560270102
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  • 9
    Electronic Resource
    Electronic Resource
    A non-empirical molecular orbital study of valence tautomers of C2H3N (1977)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 12 (1977), S. 355-368 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The valence tautomers of C2H3N have been examined by non-empirical molecular orbital calculations using two split-valence shell basis sets. All geometries were fully optimized using the 4-31G basis set and these structures were then used in 6-31G basis set calculations. The order of stability of the three possible cyclic isomers is 1-azirine 〉 cyclic carbene 〉 2-azirine. The profiles for conversion of vinylmethylene into cyclopropene, vinylnitrene into 1-arizine, and iminomethylene into 2-azirine have all been shown to have barriers.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560120212
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  • 10
    Electronic Resource
    Electronic Resource
    An ab initio molecular orbital study of the deprotonation of amines (1978)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 13 (1978), S. 349-366 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The geometries of the amines NH2X and amido anions NHX-, where X = H, CH3, NH2, OH, F, C2H, CHO, and CN have been optimized using ab initio molecular orbital calculations with a 4-31G basis set. The profiles to rotation about the N—X bonds in CH3NH-, NH2NH-, and HONH- are very similar to those for the isoprotic and isoelectronic neutral compounds CH3OH, NH2OH, and HOOH. The amines with unsaturated bonds adjacent to the nitrogen atoms undergo considerable skeletal rearrangement on deprotonation such that most of the negative charge of the anion is on the substituent. The computed order of acidity for the amines NH2X is X = CN 〉 HCO 〉 F ≈ C2H 〉 OH 〉 NH2 〉 CH3 〉 H and for the reaction NHX- + H+ → NH2X the computed energies vary over the range 373-438 kcal/mol.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560130308
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