Complexes of sulfuric acid with N,N-dimethylformamide: An ab initio investigation

The (H2SO4)(2), H2SO4-DMF, and (H2SO4)(2)-DMF complexes have been investigated, using the B3LYP functional with cc-pVQZ basis set. The characteristics of structure and energetics for binary complexes of sulfuric acid with dimethylformamide (DMF) have been obtained for the first time. The H-bond formation both between molecules of sulfuric acid as well as sulfuric acid-DMF were studied, on the basis of Weinhold's natural bond orbital (NBO) analysis. It was shown that the H-bond formation between sulfuric acid and DMF molecules is stronger than ones for the acids dimer. The value of charge transfer from lone pair (LP) orbitals of DMF oxygen to the antibonding orbital of acid OH-bond significantly exceeds the criterion of H-bond existance (0.01 e). As follows from energy, among the complexes under investigation the most preferable one was found to be (H2SO4)(2)-DMF in which sulfuric acid molecules are linked with each other by three H-bonds.