Torsional barriers in biphenyl, 2,2'-bipyridine and 2-phenylpyridine
Abstract
The rotational barriers for biphenyl, 2,2'-bipyridine and 2-phenylpyridine were calculated with HF, B3LYP, BPW91, and MP2 and double-zeta polarized basis sets. The methods differ significantly in the near-planar region, and are in close agreement otherwise, with DFT results similar to experiment over the whole range (for biphenyl). Steric repulsions, stabilizing C-H-N' interactions, π-conjugation and electron correlation give rise to DFT-calculated dihedrals for biphenyl of about 40° and similar 0° and 90° barriers, dihedrals of 23° and an almost non-existent 0° barrier for 2-phenylpyridine and two minima for 2,2'-bipyridine, which is strongly stabilized by two C-H-N' interactions in the coplanar conformation with anti-standing nitrogens.
- Publication:
-
Chemical Physics Letters
- Pub Date:
- May 2000
- DOI:
- 10.1016/S0009-2614(00)00352-3
- Bibcode:
- 2000CPL...321..399G