Abstract Crystal structures of bis(3-nitroanilinium) hexachloridostannate monohydrate, (H3NA)2SnCl6·H2O, was determined by means of X-ray single crystal diffraction. Relaxed potential energy surface of the H3NA+ ion was calculated at the B3LYP/6-31(d,p) level. The energy of the H3NA+ ion is approximately independent upon rotation of the ammonio group. It significantly depends on relative position of the nitro group towards aromatic ring. Theoretical spectra were calculated for the [(A-H3NA)Cl5·H2O]4– and [(B-H3NA)Cl5]4– anions, and thus hydrogen bonds of the ammonio group with the nearest neighboring atoms were included. PED results revealed that no coupling among all of the N–H oscillators exists. They vibrate separately because each hydrogen atom of the ammonio group of A- and B-H3NA+ ions has different surroundings of the acceptors. Overall, very good agreement between theoretical and experimental frequencies was achieved.