Density functional theory study of the hydrogen bonding interaction of 1:1 complexes of formamide with hydrogen peroxide

For the first time, the hydrogen bonding of 1:1 complexes formed between formamide and hydrogen peroxide molecule have been completely investigated in the present study using density functional theory (DFT), second-order Moller-Plesset Perturbation (MP2) and Hartree-Fock (SCF) method at varied basis set levels from 6-31g to 6-31++g(d,p). Five reasonable geometries on the potential energy hypersurface of formamide and hydrogen peroxide system are considered with the global minimum being a cyclic double-hydrogen bonded structure. The relative stability order of the five structures is FH1>FH2>FH3>FH4≈FH5. The infrared spectrum frequencies, IR intensities and the vibrational frequency shifts are reported. Finally the solvent effects on the geometries of the formamide-hydrogen peroxide complexes have also been investigated using self-consistent reaction-field (SCRF) calculations at the B3LYP/6-31++g(d,p) level. The results indicate that the polarity of the solvent has played an important role on the structures and relative stabilities of different isomers. In water, FH2 disappears and the relative stability order changes to FH3>FH1>FH5≈FH4 which is not in consistent with the gas phase one.