Triple-decker transition metal complexes bridged by a single carbocyclic ring

Triple-decker organometallic complexes of transition metals have attracted interest since 1972, when Werner and Salzer prepared the tris(cyclopentadienyl)dinickel cation, the first example of this class of compound. This paper reviews the literature for those triple-decker complexes which contain a single carbocyclic ligand bridging two metal centres.