X-ray, vibrational and theoretical studies of weak hydrogen bonds in bis(4-nitroanilinium) hexachloridostannate

• Crystal structure of bis(4-nitroanilinium) hexachloridostannate was determined.
• Potential energy surface showed very low barrier upon rotation of the NH3+ group.
• Vibrational theoretical spectra were analyzed for the [(H4NA)Cl4O]5− anion.
• Elementary graph-set descriptors are used to describe hydrogen bonding patterns.

Crystal structure of bis(4-nitroanilinium) hexachloridostannate, (H4NA)2SnCl6, was determined by means of X-ray single crystal diffraction. In the crystal structure, weak N–H…Cl hydrogen bonds are present. These interactions were taken into consideration in calculations of vibrational spectra for the [(H4NA)Cl4O]5− anion. Very good agreement between theoretical and experimental frequencies was achieved. The calculations were done at the B3LYP/6-311 + G(2d,1p) level including Grimme’s correction for dispersion. The relaxed potential energy surface indicated that the energy of H4NA+ ion is approximately independent upon rotation of the ammonio group. The energy barrier is 0.01 kcal/mol. Therefore the position of the ammonio group can be easily modified the other interacting molecules during molecular self-assembly and crystal growth processes. The energy of the H4NA+ ion significantly depends on the relative position of the nitro group towards the aromatic ring. The energy barrier of the nitro group is 4.35 kcal/mol.

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