The Cu-pyridine and Cu-(pyridine)2 complexes were studied by quantum chemical calculations. Although pyridine provides both σ and π-bonding capabilities towards metal atoms and ions, the mono-ligand and di-ligand Cu-pyridine complexes are determined to be σ- structures. In the di-ligand complex, the two pyridine rings prefer the eclipsed to the staggered form. Due to an additional Cu-N σ-bond and stronger ligand π-electron donation, the di-ligand complex possesses a stronger metal ligand interaction than the mono-ligand complex. Upon ionization, the metal-ligand bonding in the di-ligand complex is more strongly enhanced compared to the mono-ligand complex.
Copper, Pyridines, Quantum chemical calculations, Metal-ligand bonding