AB-INITIO STUDY OF THE HYDROGEN-BONDING BETWEEN PYRROLE AND HYDROGEN-FLUORIDE - A COMPARISON OF NH-CENTER-DOT-CENTER-DOT-CENTER-DOT-F AND FH-CENTER-DOT-CENTER-DOT-CENTER-DOT-PI INTERACTIONS

The structures, vibrational frequencies, and association energies of t he NH ... F and FH ...pi hydrogen-bonding complexes between pyrrole an d hydrogen fluoride have been examined using the Hartree-Fock, Moller- Plesset (second order), and density functional theory. Full geometry o ptimization and energetics of these complexes are calculated using the 6-31G, 6-31G**, 6-31+G*, 6-31+G**, 6-311G*, and 6-311++G** basis set s. The DFT calculations are carried out using the BLYP and B3LYP nonlo cal exchange-correlation functionals. After BSSE (basis set superposit ion error) by the counterpoise (CP) method and ZPVE corrections, the a ssociation energies of the pi-type and NH ... F hydrogen-bonding compl exes are calculated to be about 3.054 and 1.518 kcal/mol, respectively , at the MP4(SDTQ)/6-311++G*//MP2/6-31+G* level. The intermolecular i nteraction potential of the ct-type hydrogen-bonding complex is also d iscussed.