Directed Dynamic Resolution of an Atropisomeric Silver Complex in Solution: Role of π-π Interactions

Area of Science:

• Coordination Chemistry
• Supramolecular Chemistry
• Chiral Resolution

Background:

• Atropisomeric metal complexes present challenges in chiral resolution.
• Conventional methods like diastereomeric salt formation can be inefficient.
• Controlling stereochemistry in solution prior to isolation is an unmet need.

Purpose of the Study:

• To develop a directed dynamic resolution process for atropisomeric metal complexes.
• To achieve stereochemical control via enantiomeric interconversion in solution.
• To utilize noncovalent interactions for selective enantiomer stabilization.

Main Methods:

• Employing a directed dynamic resolution strategy for an atropisomeric silver(I) bis(N-heterocyclic carbene) complex.
• Utilizing enantiopure binaphthalene-based borate anions to induce selective π-π interactions in solution.
• Characterizing conformational dynamics and molecular locking using Nuclear Magnetic Resonance (NMR) spectroscopy.
• Crystallizing the stabilized enantiomer to isolate the resolved stereochemistry.

Main Results:

• Successful chiral resolution of an atropisomeric [Ag(NHC)2]+ complex was achieved.
• Enantiomeric interconversion was directed and controlled in solution prior to crystallization.
• Selective stabilization of one enantiomer was accomplished through π-π interactions with chiral borate anions.
• NMR spectroscopy confirmed conformational locking and restricted dynamics, correlating with the resolved stereochemistry upon crystallization.

Conclusions:

• Noncovalent interactions can effectively modulate molecular conformational dynamics for chiral resolution.
• Directed dynamic resolution in solution offers a powerful alternative to conventional methods.
• This approach provides a new strategy for accessing enantiopure atropisomeric metal complexes.