Which of the following is a \(\pi \)-donor ligand?
Answer & explanation
Correct answer: option 2
The correct answer is option 2. Cl-.
Only Cl- is a \(\pi \)-donor ligand. CN- and CO are both sigma-donor ligands, but they do not have any vacant p orbitals that can accept electrons from the metal.
\(\pi \)-donor ligands are ligands that can donate electrons to the metal's empty p orbitals. This results in a \(\pi \) bonding interaction, which strengthens the metal-ligand bond.
Cl- has a lone pair of electrons that can donate to the metal's empty p orbitals. This results in a \(\pi \) bonding interaction, which strengthens the metal-ligand bond.
CN- and CO do not have any vacant p orbitals that can accept electrons from the metal. Therefore, they are not \(\pi \)-donor ligands.