Sandwich Compound
An organometallic compound in which a metal atom is held between two parallel planar cyclic ligands.
Formula / equation
e.g. Fe(C₅H₅)₂
Unit
Dimensionless
In depth
The rings bind through their entire delocalised pi system rather than through any single carbon, a bonding mode denoted eta-5 for cyclopentadienyl. The discovery of ferrocene in 1951 and the elucidation of its structure launched modern organometallic chemistry.
Examples in the real world
Ferrocene, an orange, air-stable solid; dibenzenechromium with two benzene rings.