Experimental (FT-IR and FT-RS) and theoretical (DFT) studies of molecular structure and internal modes of [Mn(NH3)6](NO3)2

Fourier-transform Raman and infrared spectra of [Mn(NH3)6](NO3)2 were recorded and interpreted by comparison with respective theoretical spectra calculated using DFT method. The [Mn(NH3)6]2+ cation equilibrium geometry with C1 symmetry, harmonic vibrational frequencies, infrared and Raman scattering intensities were determined using B3LYP/LAN2LTZ+/6-311+G(d,p) level of theory. The band assignment was based on potential energy distribution (PED) of normal modes. The computations of NO3− anion frequencies were performed under assumption of D3h symmetry, using 6-311+G(d,p) basis set. In order do draw a comparison, additional calculations were performed separately for the [Cd(NH3)6](NO3)2 and [Ni(NH3)6](NO3)2. The computations were also carried out using selected modern exchange-correlation functionals. A sufficient general agreement between the theoretical and the experimental spectra has been achieved.