Halogen Bonds in 2,5-Dihalopyridine-Copper(I) Halide Coordination Polymers

Area of Science:

• Supramolecular Chemistry
• Coordination Chemistry
• Halogen Bonding

Background:

• Halogen bonding plays a crucial role in crystal engineering and supramolecular assembly.
• Understanding halogen bond interactions in metal-organic complexes is key to designing novel materials.

Purpose of the Study:

• To characterize 2,5-dihalopyridine-Cu(I) complexes and investigate the nature of C-X···A-Cu halogen bonds.
• To compare the strength and characteristics of halogen bonds involving different halogens at the C2 and C5 positions of the pyridine ring.

Main Methods:

• Synthesis of eight 1-D coordination polymers and one discrete structure of 2,5-dihalopyridine-Cu(I) complexes.
• Single-crystal X-ray diffraction analysis to determine the precise structural parameters of halogen bonds.
• Analysis of C-X···A-Cu and C-X···X'-C interactions within the crystal structures.

Main Results:

• The formation of 3-D supramolecular networks linked by C-X···A-Cu halogen bonds.
• C-X···A-Cu halogen bonds are found to be stronger than C-X···X'-C interactions between ligands.
• Halogen bond lengths are influenced by the electron-withdrawing nature of halogens, with C2-fluorine exhibiting shorter bonds due to its higher electronegativity.

Conclusions:

• The study provides detailed insights into halogen bonding in 2,5-dihalopyridine-Cu(I) complexes.
• The findings highlight the significant role of halogen bonding in constructing 3-D supramolecular architectures.
• The electronic effects of substituents on the pyridine ring modulate the strength and characteristics of halogen bonds.