The Hydrogen Shielding Tensors in Benzenoid Compounds - A theoretical Study

U. Fleischer

Lehrstuhl f"ur Theoretische Chemie * Ruhr-Universit"at Bochum * D-44780 Bochum * FRGermany
About sixty years ago the 'unusual' magnetic susceptibilities - as well as the anisotropies of the magnetic susceptibilities - of benzenoid hydrocarbons have been discussed qualitatively in terms of ring current models /1/.

When some twenty, thirty years later reliable data of the isotropic hydrogen chemical shifts for several of these compounds were available these data were discussed in terms some different refined models /3/.

We here report on the hydrogen shieldings tensors calculated within the IGLO approach /4/ for a series of compounds starting from benzene up to coronene. The results are compared to the available experimental (isotropic) chemical shift data and to calculations for open chain alkenes. We discuss the trends observed for the in plane and out of plane principal values of the tensors. Comparisons are made with trends observed for the magnetic susceptibilities and with results of ring current models.

Citations

  1. see e.g. references cited in /2/
  2. U. Fleischer, W. Kutzelnigg, P. Lazzeretti, V. M"uhlenkamp, J. Am. Chem. Soc., 1994 116 5298
  3. C.W. Haigh, R.B. Mallion, Mol. Phys., 1970 18 737, 751
  4. M. Schindler, W. Kutzelnigg, J. Chem. Phys., 1982 76 1919
  5. W. Kutzelnigg, U. Fleischer, M. Schindler, NMR: Basic Princ. Prog., 1990 23 165
Return to main WATOC Poster page