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(NH(3))(6)(2) were recorded and interpreted by comparison with respective theoretical spectra calculated using DFT method. The Mn(NH(3))(6) cation equilibrium geometry with C(1) 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 NO(3)(-) anion frequencies were performed under assumption of D(3h) symmetry, using 6-311+G(d,p) basis set. In order do draw a comparison, additional calculations were performed separately for the Cd(NH(3))(6)(2) and Ni(NH(3))(6)(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.