Crystal structure and vibrational spectra of bis(betaine) sulfamate

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 P2(1)/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) Angstrom) and weak N-H ... O hydrogen bonds (R(N ... O)=2.983(2)-3.028(2) Angstrom). 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.