what is Ferrocene ?

Ferrocene Fe(C5H5)2 is the prototypical metallocene, a type of organometallic chemical compound, consisting of two cyclopentadienyl rings bound on opposite sides of a central iron atom and forming an organometallic sandwich compound .
Ferrocene was first made unintentionally from the reaction of cyclopentadiene and iron powder in the 1950's, originally designed to couple the diene. Instead a lightly orange powder was obtained. The structure was confirmed by NMR. Led to an explosion of interest in d-block metal carbon bonds and brought about development and the now flourishing study of organometallic chemistry.
Ferrocene is used as a combustion control additive in fuels, antiknock agent in gasoline, and for heat stabilization in greases and plastics. It is used as a catalyst for the synthesis of ammonia. Intensive study of metal-carbon bonds have been developed in the field of electrochemical techniques, high-temperature chemistry, photolysis chemistry, structural chemistry, organic light-emitting devices, biochemistry and pharmaceutical manufacturing.