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Z Smiatacz - One of the best experts on this subject based on the ideXlab platform.

Hans-jörg Schneider - One of the best experts on this subject based on the ideXlab platform.

  • Non-Covalent Interactions of Organic Halogen Compounds with Aromatic Systems – Analyses of Crystal Structure Data
    European Journal of Organic Chemistry, 2005
    Co-Authors: Dariusz Swierczynski, Grigori Dolgonos, Roman Luboradzki, Janusz Lipkowski, Hans-jörg Schneider
    Abstract:

    The Cambridge Structural Database showed in mid 2002 about 20.000 Structures containing halogen atoms and aryl rests with distances d between the aryl center and the halogen atom, which would allow both hydrogen bonds with the aromatic hydrogens and/or van der Waalsinteractions with the π-cloud. The latter are characterized by short distances d and by small angles α between the vector along the aryl centroid–halogen line and the perpendicular vector originating in the aryl center (the plane normal). The cases with d 60° (about 40 % of the fragments), with only very few cases close to linear hydrogen bonds (then with α = 90°). Compounds containing metal–halogen bonds were omitted in view of possible strong orientational interferences. The Structures were screened with four different halogen binding modes, all of them containing the halogen attached to a carbon atom, but with different hybrizations at the connecting carbon centers. The results show only small differences in the distance distributions, with a slight preference for smaller α values for sp2 frameworks. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

  • non covalent interactions of organic halogen compounds with aromatic systems analyses of Crystal Structure Data
    European Journal of Organic Chemistry, 2005
    Co-Authors: Dariusz Swierczynski, Grigori Dolgonos, Roman Luboradzki, Janusz Lipkowski, Hans-jörg Schneider
    Abstract:

    The Cambridge Structural Database showed in mid 2002 about 20.000 Structures containing halogen atoms and aryl rests with distances d between the aryl center and the halogen atom, which would allow both hydrogen bonds with the aromatic hydrogens and/or van der Waalsinteractions with the π-cloud. The latter are characterized by short distances d and by small angles α between the vector along the aryl centroid–halogen line and the perpendicular vector originating in the aryl center (the plane normal). The cases with d 60° (about 40 % of the fragments), with only very few cases close to linear hydrogen bonds (then with α = 90°). Compounds containing metal–halogen bonds were omitted in view of possible strong orientational interferences. The Structures were screened with four different halogen binding modes, all of them containing the halogen attached to a carbon atom, but with different hybrizations at the connecting carbon centers. The results show only small differences in the distance distributions, with a slight preference for smaller α values for sp2 frameworks. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

H. L. Bhat - One of the best experts on this subject based on the ideXlab platform.

V. Venkataramanan - One of the best experts on this subject based on the ideXlab platform.

Joel F. Liebman - One of the best experts on this subject based on the ideXlab platform.

  • Volumes of solid state ions and their estimation.
    Inorganic chemistry, 2005
    Co-Authors: H. Donald Brooke Jenkins, Joel F. Liebman
    Abstract:

    Formula unit volume, Vm, has recently been identified as the key link to a number of thermodynamic functions and has given rise to an alternative approach to thermodynamics for modern inorganic materials (volume-based thermodynamics, VBT). In an earlier publication, we reported over 400 ion volumes for commonly encountered cations and anions derived from Crystal Structure Data which can, in turn, be used to generate formula unit volumes for those ionic salts, for which Crystal Structure Data, which is the preferred source of such volume Data, is not available. The purpose of the present paper is to report a further 147 supplementary ion volumes. These are compared to ion volumes obtained from the summation of Hofmann's elemental volumes, a convenient and alternative approach for the estimation of Vm. It is shown that many elusive ion volumes can be estimated using these Databases in tandem by adopting the newly proposed isomegethic rule and other volume additivity rules. Generation of volume Data for new, hypothetical, and counterintuitive ions, as well as for traditional ions, is now a reality, as is demonstrated.