Anilinium monohydrogen DL-malate

Area of Science:

• Crystallography
• Supramolecular Chemistry
• Computational Chemistry

Background:

• Anilinium salts often exhibit rotational disorder of the ammonium group at room temperature.
• Understanding hydrogen bonding in organic salts is crucial for predicting crystal structures.
• Malate ions are biologically relevant molecules involved in metabolic pathways.

Purpose of the Study:

• To characterize the crystal structure of anilinium DL-malate.
• To investigate the role of hydrogen bonding in the observed crystal packing.
• To compare the solid-state conformation of the malate ion with theoretical predictions.

Main Methods:

• Single-crystal X-ray diffraction analysis.
• Analysis of hydrogen bonding networks and intermolecular interactions.
• Ab initio molecular orbital calculations for conformational analysis.

Main Results:

• The crystal structure consists of protonated anilinium cations and monodissociated DL-malate anions.
• The anilinium N-H groups form hydrogen bonds with malate oxygens, restricting NH3+ rotation.
• Malate anions form 2D hydrogen-bonded sheets parallel to the (001) plane.
• Anilinium cations and malate sheets form 2D layers with phenyl rings perpendicular to malate sheets.
• The crystal conformation of the malate ion was determined and compared to theoretical calculations.

Conclusions:

• The study elucidates the ordered structure of anilinium DL-malate, driven by specific hydrogen bonding interactions.
• The restricted rotation of the anilinium group is a key feature distinguishing it from other anilinium salts.
• The findings provide insights into the supramolecular assembly of organic salts and validate computational methods for conformational analysis.