Bidentate Ligand
A ligand that binds to the same metal centre through two donor atoms, forming a ring.
Unit
Dimensionless
In depth
Bidentate ligands occupy two coordination sites and create a chelate ring, most stably of five or six atoms, since these are free of ring strain. Complexes with bidentate ligands can be optically active because the arrangement of the rings can be non-superimposable.
Examples in the real world
Ethane-1,2-diamine (en), the oxalate ion, and the bipyridyl ligand of many photocatalysts.