Structure and conformation of 4,4 '-bipyridine

The title compound has been investigated by x-ray analysis and AM1 semiempi rical quantum mechanical method. The geometry of the two molecules in the a symmetric unit is different in terms of the torsion angle theta [ C4-C5-C6- C10 ]between the two pryidine rings which is -34.1 (2)degrees and -17.9 (2) degrees in molecule I and II respectively. The conformation of the energy p rofile showed that the minimum energy conformation has the torsion angle th eta near 35 degrees. The crystal structure is stabilized by C-H ... N hydro gen bonds.