THE MOLECULAR-STRUCTURE OF 1,3-BUTADIEN-1-OL AND 1,3-BUTADIEN-2-OL - AN AB-INITIO SCF-MO STUDY

Ab initio SCF-MO calculations at the 3-21G level with full geometry op timization were performed for the three isomers of 1,3-butadienol. Imp roved energy estimates were obtained with single-point calculations at the 6-31G and MP2/6-31G* levels of theory. The critical points for r otation about the central C-C bond were located for both configuration s of the OH group. trans-Butadien-1-ol has stable gauche forms (theta = 39-degrees), with gauche-trans energy differences of ca. 10 kJ mol-1 , very close to the reported values for butadiene itself. The energies and geometries of the less stable conformers of cis-butadien-1-ol and butadien-2-ol are strongly dependent on the OH group configuration, l ying ca. 1.3-15.5 kJ mol-1 above the s-trans minima, with theta values ranging from 0-degrees to 43.5-degrees.