Crystal structure and vibrational spectra of bis(betaine) sulfamate

Abstract

The crystal structure of bis(betaine) sulfamate (BBAS) has been determined by X-ray diffraction method at 250 and 100 K as monoclinic, space group P2₁/c, Z=4. The crystal comprises of monoprotonated betaine dimers and sulfamate anions NH₂SO₃⁻. Two kinds of hydrogen bonds are present in the crystal: strong, symmetric and linear O···H···O hydrogen bonds (R(O···O)=2.448(2)–2.442(2) Å) and weak N–H···O hydrogen bonds (R(N···O)=2.983(2)–3.028(2) Å). At low temperature (100 K) the BBAS structure is completely ordered. At 250 K 5% of sulfamate anions have their orientation changed through inversion of the NH₂ groups. Infrared transmission (for both BBAS and the deuterated from, DBBAS), reflection and Raman spectra of the title compound have been recorded and discussed in relation to the X-ray crystal structure. Additionally, temperature dependence of the BBAS infrared spectra in the 12–300 K range was investigated on purpose to find a possible relation between structural and spectroscopic changes in the studied crystal.