What are pi donor ligands also known as?

Pi donor ligands are also referred to as pi bases. These ligands have lone pairs of electrons that are capable of participating in coordination with a metal center, typically through back donation. This interaction is characterized by the donation of electron density from the ligand's pi orbitals into vacant orbitals of the metal, effectively forming coordinate covalent bonds.

In the context of coordination chemistry, pi donor ligands enhance stabilization of metal complexes by allowing for the formation of π-backbonding, where electron density is also transferred back to the ligand from the metal. Classic examples of pi donor ligands include olefins and acetylides.

Understanding that pi donor ligands are classified as pi bases is essential for grasping concepts related to complex stability, reactivity, and electronic structure in metal-ligand interactions. This classification helps explain the behavior and properties of such ligands in various coordination environments.