An ab initio investigation of 2-amino-2-imidazoline: A key moiety in chemical and biochemical processes

The 2-amino-2-imidazoline moiety is currently used not only in drugs, but a lso in insecticides, and fungicides. Ab initio calculations are performed t o evaluate the molecular properties of the two tautomeric forms and the pro tonated form with extended basis sets ranging from 6-31G* to 6-311+ +G** at Hartree-Fock and density functional (BLYP and B3LYP) levels. Moller-Plesse t perturbation is tested at the MP2/6-31G* level only. Optimized geometry s tructures, energies and thermochemical properties are generated. Basis set and correlation effects on geometries, tautomer equilibrium constant and pr otonation enthalpy are carefully analysed. Although observed for the isolat ed molecule, these results may be extrapolated to chemical and biochemical systems of interest.