Synthesis of Spirocyclic Diphosphite-Supported Gold Metallomacrocycles via a Protodeauration/Cyclization Strategy:...

Area of Science:

• Organometallic Chemistry
• Supramolecular Chemistry
• Coordination Chemistry

Background:

• Gold-phosphine complexes are valuable in catalysis and materials science.
• The synthesis of complex metallomacrocycles remains a significant challenge.
• Understanding self-assembly processes is key to designing novel molecular architectures.

Purpose of the Study:

• To synthesize P-metalated bimetallic gold complexes and metallomacrocycles using a spirocyclic diphosphite.
• To investigate the mechanism of metallomacrocycle formation and identify key intermediates.
• To explore the structural and binding properties of the synthesized metallomacrocycles.

Main Methods:

• Protodeauration reactions utilizing gold precursors.
• NMR spectroscopy and high-resolution mass spectrometry for mechanistic studies.
• X-ray crystallography for structural determination of metallomacrocycles.

Main Results:

• Stepwise synthesis of bimetallic complexes achieved.
• Complex, reversible ligand redistribution reactions observed during metallomacrocycle formation.
• Flexible diphosphine linkers critical for selective metallomacrocycle synthesis; rigid linkers yielded mixtures.
• X-ray structure revealed an unsymmetrical collapsed form of a 32-membered metallomacrocycle with aurophilic interactions.
• Solution structure suggested dynamic interconversion between forms.
• The metallomacrocycle effectively bound estrogen via Au-P-O hydrogen bonds.

Conclusions:

• Spirosylic diphosphites are effective reagents for constructing gold-phosphine bimetallic complexes and metallomacrocycles.
• Flexible diphosphine linkers are essential for the controlled self-assembly of metallomacrocycles.
• The synthesized metallomacrocycles exhibit interesting structural dynamics and potential for molecular recognition, such as estrogen binding.