Pronunciation: (fer'u-sēn"),[key] —n.Chem. 1. Also called dicyclopentadienyliron. an orange, crystalline, water-insoluble coordination compound, (C5H5)2Fe, having a camphorlike odor: used chiefly as an antiknock agent for gasoline and as a catalyst. Cf. metallocene. 2. Also called dicyclopentadienyl metal. any of a class of analogous compounds containing a metal other than iron, as nickel or osmium.