Sandwich compounds

Half-sandwich compounds

Half sandwich complexes have only one facially-bound planar organic ligand instead of two gives rise to a still larger family of half-sandwich compounds. One well studied example is probably methylcyclopentadienyl manganese tricarbonyl. Such species are occasionally referred to as piano-stool compounds, at least when there are three diatomic ligands. In such cases, the facially-bound planar organic ligand comprises the "seat" of the piano stool.