what are ligands

Ligands are molecules or ions that bind to a central metal atom or ion to form a coordination complex/Coordination_Chemistry/Structure_and_Nomenclature_of_Coordination_Compounds/Ligands). They act as Lewis bases, which means they donate a pair of electrons to the central metal atom or ion, which acts as a Lewis acid, or electron pair acceptor/Coordination_Chemistry/Structure_and_Nomenclature_of_Coordination_Compounds/Ligands). Ligands can be anions, cations, or neutral molecules, and they can be characterized as monodentate, bidentate, tridentate, etc., depending on the number of binding sites with the central metal atom/Coordination_Chemistry/Structure_and_Nomenclature_of_Coordination_Compounds/Ligands). Examples of ligands include F–, Cl–, Br–, I–, S2–, CN–, NCS–, OH–, NH2–, NH3, H2O, NO, CO, NO+, N2H5+, and many others/Coordination_Chemistry/Structure_and_Nomenclature_of_Coordination_Compounds/Ligands). In biochemistry, a ligand is any molecule or atom that irreversibly binds to a receiving protein molecule, otherwise known as a receptor.