l-Glutamic acid hydro-chloride at 153 K

Area of Science:

• Crystallography
• Structural Chemistry
• Materials Science

Background:

• Previous crystallographic studies of (S)-1,3-dicarboxy-propanaminium chloride by Dawson and Sequeira et al. provided initial structural data.
• These earlier investigations had limitations, including the absence of hydrogen atom locations and less precise structural parameters.

Purpose of the Study:

• To refine the crystal structure of (S)-1,3-dicarboxy-propanaminium chloride at low temperature (153 K).
• To accurately locate all hydrogen atoms and characterize the hydrogen bonding network within the crystal lattice.

Main Methods:

• Single-crystal X-ray diffraction at 153 K.
• Refinement of crystallographic data to a residual R-factor of 0.017.
• Full localization of all hydrogen atoms in the structure.

Main Results:

• A highly accurate crystal structure determination with R = 0.017.
• Identification of distinct C-C bond lengths compared to prior studies.
• Observation of protonation of l-glutamic acid and its interaction with the chloride anion via an O-H⋯Cl hydrogen bond.
• Characterization of a 3D network of O-H⋯O, N-H⋯O, and N-H⋯Cl hydrogen bonds.

Conclusions:

• The present study provides the most precise structural data to date for (S)-1,3-dicarboxy-propanaminium chloride.
• The detailed hydrogen bonding network plays a crucial role in stabilizing the crystal structure.
• Discrepancies in C-C bond lengths highlight the importance of accurate structural determination, especially with hydrogen atom localization.