Ab initio HF-SCF studies of the equilibrium structures and vibrational spectra of the Be(NO 3) 2, Mg(NO 3) 2 and Ca(NO 3) 2 molecules

Abstract

HF-SCF calculations have been performed for the Mg(NO 3) 2, Ca(NO 3) 2 and Be(NO 3) 2 molecules to determine their stable equilibrium structures and vibrational spectra. Bidentate and monodentate structures have been taken into account and the calculations suggest that non-planar D 2 d is the most stable equilibrium structure for all the species considered in the work. The infrared spectra of the D 2 d and D 2 h structures of Mg(NO 3) 2 have been simulated on the basis of the HF/6–31G ∗ frequency and intensity calculations, and the 18O isotope shifts have been predicted in the stretching region of the NO 3 − modes. The conclusions of the calculations have been used to assign the FT-IR spectra of molecular Cu(NO 3) 2. The paper includes calculations for the [BeNO 3] +H 2O, [MgNO 3] +H 2O, [CaNO 3] +H 2O, [AlNO 3] 2+H 2O, [BeNO 2] +H 2O, [MgNO 2] +H 2O, [CaNO 2] +H 2O, and [AlNO 2] 2+H 2O hydrated species.