STRUCTURE, ENERGETICS AND BONDING OF DIACETYLENE COMPLEXES WITH HYDROGEN-FLUORIDE - A THEORETICAL INVESTIGATION

Ab initio calculations have been carried out on diacetylene-HF complex es both at the SCF and second-order Moller-Plesset level using a 6-31 + + G(d, p) basis set to determine the structures and association ener gies of the various possible forms of the complexes. The non-symmetric pi complex has been found to be the most stable but the energy differ ence between the symmetric pi and the reverse sigma complex is small. The hydrogen bond lengths at the MP2 level are shorter by about 0.3 to 0.7 bohr than the respective SCF ones. Molecular electrostatic potent ial and electron density based topographical analyses, and qualitative model studies, have been carried out to elucidate the nature and stre ngth of the bonding involved.