MOLECULAR-ORBITAL CALCULATIONS OF THE ROTATIONAL BARRIER IN BENZENESELENENYL MOLECULES

Structural changes, as a function of the torsional angle about the phe nyl-Se bond, in molecules of the type C6H5Se-X, where X is H, Br, Cl, have been studied by ab initio calculations using the 3-21G and 3-21G basis sets. The results are compared with the equilibrium structure a vailable from electron diffraction experiments as well as with previou s calculations for the sulfur and oxygen analogs where X = H. The rota tional potential energy function and the rotational barriers are also reported.