COMPARISON BETWEEN THE s-CIS AND GAUCHE CONFORMERS OF 1,3-BUTADIENE.

Geometries of stationary points for s-cis-1,3-butadiene and gauche-1,3-butadiene have been predicted via molecular electronic structure theory. Both double- zeta (DZ) and double- zeta plus polarization (DZ plus P) basis sets were used in conjunction with the self-consistent-field (SCF) and configuration interaction (CI) methods. At the DZ SCF level, s-cis-1,3-butadiene was characterized as a transition state for the isomerization of the two possible gauche-1,3-enantiomers, which were shown to be genuine local minima. The barrier to planarity at this level of theory was predicted to be 0. 4 kcal/mol, and the torsional angle for the gauche structure is 33. 2 degree .The same qualitative result was found at the DZ plus P SCF level, with the rotational barrier being 0. 7 kcal and the torsional angle 37. 8 degree .SCOPUS: NotDefined.j