Discriminating the structure of exo-2-aminonorbornane using nuclear quadrupole coupling interactions

  1. Écija, P. 2
  2. Cocinero, E.J. 2
  3. Lesarri, A. 3
  4. Millán, J. 1
  5. Basterretxea, F. 2
  6. Fernández, J.A. 2
  7. Castaño, F. 2
  1. 1 Universidad de La Rioja

    Universidad de La Rioja

    Logroño, España

    ROR https://ror.org/0553yr311

  2. 2 Universidad del País Vasco/Euskal Herriko Unibertsitatea

    Universidad del País Vasco/Euskal Herriko Unibertsitatea

    Lejona, España

    ROR https://ror.org/000xsnr85

  3. 3 Universidad de Valladolid

    Universidad de Valladolid

    Valladolid, España

    ROR https://ror.org/01fvbaw18

Journal of Chemical Physics

ISSN: 0021-9606

Year of publication: 2011

Volume: 134

Issue: 16

Pages: 164311-164318

Type: Article

DOI: 10.1063/1.3583494 SCOPUS: 2-s2.0-79955698149 WoS: WOS:000290047600022 GOOGLE SCHOLAR

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The intrinsic conformational and structural properties of the bicycle exo-2-aminonorbornane have been probed in a supersonic jet expansion using Fourier-transform microwave (FT-MW) spectroscopy and quantum chemical calculations. The rotational spectrum revealed two different conformers arising from the internal rotation of the amino group, exhibiting small (MHz) hyperfine patterns originated by the 14N nuclear quadrupole coupling interaction. Complementary ab initio (MP2) and DFT (B3LYP and M05-2X) calculations provided comparative predictions for the structural properties, rotational and centrifugal distortion data, hyperfine parameters, and isomerization barriers. Due to the similarity of the rotational constants, the structural assignment of the observed rotamers and the calculation of the torsion angles of the amino group were based on the conformational dependence of the 14N nuclear quadrupole coupling hyperfine tensor. In the most stable conformation (ss), the two amino N-H bonds are staggered with respect to the adjacent C-H bond. In the second conformer (st), only one of the N-H bonds is staggered and the other is trans. A third predicted conformer (ts) was not detected, consistent with a predicted conformational relaxation to conformer ss through a low barrier of 5.2 kJ mol -1. © 2011 American Institute of Physics.