Structure and polarized IR and Raman spectra of the solid complex of bis(betaine)—sulphuric acid

Abstract

The crystal structure of bis(betaine)—sulphuric acid has been determined by X-ray diffraction as orthorhombic, space group Pbca, with a = 11.442(2), b = 22.710(5), c = 11.941(2)Å and Z = 8. The crystal comprises bisulphate ions, HSO−4, and two distinct betaine molecules, which are held in a complex by short hydrogen bonds. One of the betaine molecules is present as the zwitterion form (CH3)3N+CH2COO− and the second occurs as the protonated form (CH3)3N+CH3COOH. Powder FTIR and polarized infrared and Raman spectra of the single crystal were measured. An assignment of the observed bands to vibrations of the hydrogen bonds and internal vibrations of the bisulphate ion and the betaine moleccules is proposed.