Theoretical studies on the topographical features and energetics of diacetylene-hydrogen fluoride complexes

Ab initio supermolecular SCF calculations have been carried out on diacetylene-HF complexes at the STO-4-31G level. The reverse σ (Rσ) complex has been found to have the lowest energy. Of the two π complexes. T and L, the symmetrical one T is found to be energetically less stable than the asymmetrical one L. Theoretical vibrational analysis tends to support this stability order. Electrostatic interaction energy calculations also lead to an almost identical sequence. Hydrogen bond energies corrected for basis set superposition error indicate that ΔE_H (Rσ) > ΔE_H (Tπ) ≈ ΔE_H (Lπ).