THEORETICAL-STUDIES ON THE HYDROGEN-BONDED UREA-PHENOL COMPLEXES - THE MIXED BASIS-SET APPROACH

The quantum-chemical calculations within one electron approximation ba sed on restricted Hatree-Fock method (RHF) and at the level of second order Moller-Plesset perturbation theory (MP2) were performed for hydr ogen bonded phenol-urea complexes. The mixed basis set approach yields also for neutral systems results close to calculations carried out wi th fully extended basis sets. The theoretical findings are compared wi th experimental data available for linear complex. The most stable com plexes of gaseous urea and phenol are those with cyclic hydrogen bonds .