Early transition metal fulvalene complexes

Homo- and heterobimetallic complexes containing hydrocarbons as bridging ligands have become increasingly interesting. Metal atoms that are held in close proximity connected by bridging ligands exhibit unique properties and many of these compounds have been tested for their particular reactivity. The fulvalene ligand has the ability to coordinate two proximal metal centres and in an effort to search for new chemical and physical properties a series of transition metal derivatives have been exhaustively described. In this review we will focus on groups 4 and 5 transition metal complexes incorporating a fulvalene bridging system. After considering general aspects in the Introduction section, we describe general synthetic methods, chemical and structural properties and the reactivity of the corresponding compounds.