Structural and thermal study of solvent-free tetrabutylammonium chloride and its novel solvates

Abstract

Here we discuss the crystal structure of solvent-free TBACl and its solvates – TBACl∙0.5C7H8, and TBACl∙xH2O, x ≈ 0.1, obtained from single-crystal X-ray diffraction experiments and DFT calculations. Solvent-free TBACl and the hydrate crystallize in P21/n space group, with the ions adopting deformed trigonal coordination and forming layers in the (1 0 1) plane. Similar coordination is observed in TBACl∙0.5C7H8, I2/a. The hydrate is stabilized by rather strong O–H⋯Cl hydrogen bond, as it is indicated by DFT optimization required for obtaining more realistic position of water molecule. According to TGA/DSC results, dry TBACl melts at 76.3 °C (onset), with a DSC peak at 79.4 °C, and vaporizes during further heating above 170 °C, decomposing into smaller fragments, as observed in the MS spectra.