Usually binucleating ligands feature bridging ligands, such as phenoxide, pyrazolate, or pyrazine, as well as other donor groups that bind to only one of the two metal ions. Some ligands
binucleating ligands are symmetrical, which facilitates the formation of homobimetallic complexes. Other binucleating ligands, where the binding compartments are dissimilar, facilitate the formation of heterobimetallic complexes.