Acetyl-ene-ammonia-18-crown-6 (1/2/1)

Area of Science:

• Supramolecular Chemistry
• Crystal Engineering
• Inorganic Chemistry

Background:

• 18-crown-6 is a well-known macrocycle capable of forming inclusion complexes.
• Acetylene is a simple alkyne with potential for various chemical interactions.
• Liquid ammonia serves as a unique solvent for co-crystallization studies.

Purpose of the Study:

• To investigate the co-crystallization of 18-crown-6 and acetylene in liquid ammonia.
• To characterize the crystal structure and intermolecular interactions of the resulting compound.
• To explore the role of hydrogen bonding and weak interactions in crystal formation.

Main Methods:

• Co-crystallization
• Single-crystal X-ray diffraction
• Structural analysis

Main Results:

• Formation of a novel compound with the stoichiometry C(2)H(2)·C(12)H(24)O(6)·2NH(3).
• The crystal structure exhibits threefold rotoinversion symmetry with acetylene and ammonia molecules on the threefold axis.
• Intermolecular N-H⋯O hydrogen bonds connect ammonia and crown ether, while weak C-H⋯N interactions form acetylene chains along the c axis.
• The 18-crown-6 molecule is disordered and was refined using a split model.

Conclusions:

• The co-crystallization successfully formed a new supramolecular assembly.
• The crystal structure highlights the interplay of hydrogen bonding and weaker interactions in directing molecular arrangement.
• The study demonstrates the versatility of 18-crown-6 in forming complexes with small molecules under specific conditions.