Metal arene complexes are organometallic compounds of the formula (C6R6)xMLy. Common classes are of the type (C6R6)ML3 and (C6R6)2M. These compounds are reagents in inorganic and organic synthesis. The principles that describe arene complexes extend to related organic ligands such as many heterocycles (e.g. thiophene) and polycyclic aromatic compounds (e.g. naphthalene).[1]