Vibrational recognition of pyramidal formamide molecules in selected salt solutions.

Raman and IR spectroscopic measurements were carried out in formamide (FA) solutions containing variable SnCl4 contents. Pyramidal FA molecules play a major role in these media and are characterised by new bands at 1746, 1190 and 796 cm−1, which may be used as makers. The electrostatic potential (φ) of the coordinated ion shows good relationship with the arising of these bands, which are only seen in the spectra as the cation presents φ ≥ 3.9 × 1020 J C−1. Pyramidalisation of FA is due to the presence of a quaternary N in the [Sn(FA)2Cl2]2+ complex, which is formed along with [SnCl6]2-. The major Sn(IV)-based complexes are structurally similar to those commonly identified in aqueous medium. [ABSTRACT FROM AUTHOR]