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  • Calculations, ab initio  (2)
  • Ab initio computations, astatine azide  (1)
  • 1
    Electronic Resource
    Electronic Resource
    The structure of astatine azide, AtN3—A theoretical study (1997)
    Springer
    Structural chemistry 8 (1997), S. 421-423 
    Details
    ISSN: 1572-9001
    Keywords: Ab initio computations, astatine azide ; covalent azides ; halogen azides ; hybrid computations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract For the first time theoretical evidence for the experimentally hitherto unknown astatine azide, AtN3, the heaviest of all halogen azides, is presented. The structure and the vibrational data of AtN3 were computedab initio at RHF and electron-correlated MP2 levels of theory using a quasirelativistic (MWB) pseudopotential for astatine, where the basis functions for the valences andp electrons consist of the standard double-ζ basis set. For nitrogen a standard 6-31G(d) basis was used. The molecule represents a true minimum (NIMAG=0) at all levels of theory applied and is predicted to exist in a planartrans bentC s structure. Since hybrid functionals, which define the exchange functional as a linear combination of Hartree-Fock, local, and gradient-corrected exchange terms, are known to predict the experimental parameters best, we also computed astatine azide (At-N1-N2-N3) at the B3-LYP level; the results are as follows:d(At-N1)=2.267,d(N1–N2)=1.239,d(N2–N3)=1.146 å; ∠(A1-N1-N2)=111.6
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02311700
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  • 2
    Electronic Resource
    Electronic Resource
    Zerfall von Nitrosylazid, N4O: Existieren auch cyclische Stickstoff-Oxide? (1995)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 128 (1995), S. 201-203 
    Details
    ISSN: 0009-2940
    Keywords: Nitrogen oxides ; Calculations, ab initio ; Tetranitrogen monoxide ; Dinitrogen monoxide ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Decomposition of Nitrosyl Azide, N4O: Are Cyclic Nitrogen Oxides Existent?The unimolecular decomposition of nitrosyl azide (tetranitrogen monoxide), N4O, was studied at the electron-correlated, spin-restricted RMP2 level with the 6-31G(d,p) and 6-31+G* basis sets. Frequency calculations were performed at 6-31+G* on the optimized structures. It is demonstrated that the experimentally established trans-trans-N4O (Cs) may either interconvert into cis-cis-N4O which upon decomposition forms cyclic N4O (C2v) as an intermediate species to finally give N2O (C∞v) and N2, or trans-trans-N4O may directly dissociate into cyclic N2O (C2v) and N2. All structures determined were rationalized by energy hypersurface calculations.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19951280220
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  • 3
    Electronic Resource
    Electronic Resource
    The Structures of [X2Y—N—YX2]+ Cations (X = F, Cl; Y = S, Se). A Comparison of X-ray and ab Initio Studies[1] (1995)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 128 (1995), S. 35-40 
    Details
    ISSN: 0009-2940
    Keywords: Selenium-nitrogen compounds ; Sulfur-nitrogen compounds ; Calculations, ab initio ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The structures of cationic species of the series [X2Y—N—YX2]+ (X = F, Cl; Y = S, Se) have been computed ab initio using all electron treatments for first-row elements and sulfur and quasi-relativistic pseudopotentials for Se and Cl. Splitvalence basis sets with polarization and diffuse functions were employed. The MP2 results for the (non-isostructural!) cations [Cl2Se—N—SeCl2]+ (1: Cs) and [F2S—N—SF2]+ (2: C2v) are in excellent agreement with the experimental (X-ray) observations. Both structures represent local minima. A deeper minimum for either of the cations is represented by another C2v isomer which for crystal lattice energy reasons is stable in the isolated state only. The geometries of the hitherto unknown species [Cl2S—N—SCl2]+ (3) and [F2Se—N—SeF2]+ (4) have been assessed by ab initio HF calculations. In analogy to 2, cations 3 and 4 are predicted to prefer C2v symmetry. Therefore, 1 exhibits unusual structural features. According to strictly localized natural bond orbital analysis (NBO), the central nitrogen atoms in 1 and 2 possess two lone pairs of electrons (LP: one sp hybrid and one p orbital). The relatively short Se—N and S—N bond distances in 1 (1.741-1.760 Å) and 2 (1.551 Å) can best be attributed to LP(N)→s̰*(Y—X) negative hyperconjugation (1: Y = Se, X = Cl; 2: Y = S, X = F).
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19951280106
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