Theoretical study on the hydrogen bond interaction between diacetamide and methanol

The hydrogen bonding of 1:1 complexes formed between diacetamide and methanol molecule have been completely investigated in the present study using density functional theory and second order Moller–Plesset perturbation (MP2) method. Various basis sets from 6-31G to 6-311++G** have been employed to determine the equilibrium structure of the interacting complexes. Three reasonable geometries on the potential energy hypersurface of diacetamide with methanol system are considered with the global minimum being a cyclic double-hydrogen bonded structure. The optimized geometric parameters and interaction energies for various isomers at different levels are estimated showing that the two carbonyl groups have about the same proton acceptor ability. Special attention was paid to the basis set superposition error and zero-point energy corrections that were not given appropriate attention in previous studies. Finally, the solution phase studies are also carried out using the Onsager reaction field model at B3LYP/6-311++G** level for the hydrogen-bonded complex of diacetamide with methanol. The results indicate the polarity of the solvent has played an important role on the structures and relative stabilities of different isomers or the proton acceptor ability of two carbonyl groups. [Copyright &y& Elsevier]