Cyclic Homo- and Heterohalogen Di-λ³-diarylhalonium Structures

Area of Science:

• Organometallic Chemistry
• Supramolecular Chemistry
• Synthetic Organic Chemistry

Background:

• Growing interest in cyclic diaryliodonium salts.
• Limited exploration of structures with multiple hypervalent halogens within a single ring system.

Purpose of the Study:

• To present synthetic design principles for new cyclic structures containing two hypervalent halogens.
• To explore the formation of novel mixed-halogen cyclic systems.
• To synthesize and characterize larger cyclic bis-iodine(III) structures and investigate their interactions.

Main Methods:

• Oxidative dimerization of precursors with ortho-disposed iodine and trifluoroborate groups.
• Synthesis of phenylene-, naphthylene-, and xanthene-based bis-iodine(III) compounds.
• X-ray crystallography for structural analysis.
• Preliminary studies on ligand interactions using solution and solid-state methods.

Main Results:

• Successful synthesis of the smallest cyclic bis-phenylene bis-iodine(III) derivative.
• First report of cyclic structures containing two different halogen atoms (I/Br, I/Cl).
• Characterization of cyclic bis-naphthylene bis-iodine(III) and a bis-iodine(III)-macrocycle.
• Structural analysis revealed specific interplanar angles and dicationic dimerization through π-π and C-H/π interactions.
• Intramolecular bridging by triflate anions in the macrocyclic structure.
• X-ray structure confirmed chelating donor bonding of bis-pyridine ligands to a single iodine center.

Conclusions:

• Established synthetic principles for a new family of cyclic bis-hypervalent halogen compounds.
• Demonstrated the feasibility of constructing mixed-halogen cyclic systems and macrocycles.
• Provided insights into the structural features and intermolecular interactions of these novel compounds.