102-54-5 dicyclopentadienyliron

Formula (C5H5)2Fe or (ri-C5H5)2Fe MW 186.04 a metal n sandwich complex in which the six n electron system of the cyclopentadienidide ion CsHf is bound to Fe2+ ion Fe—C distance 2.045 A and C—C bond distance 1.4 A. Synonyms bis(cyclopentadienyl)iron ferrocene dicyclopentadienyliron... 

Dicyclopentadienyliron finds limited application as a catalyst. It was used earlier as an antiknock additive for gasoline. The complex also is used to synthesize other metal jr-complexes and their derivatives. 

As regards organometallics other than tetraethyllead and other lead alkyls, only iron pentacarbonyl has received much attention, because of its low cost in some fuels it is probably the cheapest known source of antiknock increase (20). However, the great increase in engine wear which its abrasive combustion products produce makes its use impractical, and there appear to be no prospects for its commercial use (20). A new iron compound, dicyclopentadienyliron (ferrocene), also demonstrates the antiknock effectiveness of iron compounds. As an antiknock, it is approximately 50% as effective as tetraethyllead and has other favorable characteristics, but it is not practical for antiknock use for the same reason as iron pentacarbonyl—accumulation of iron oxide in engine cylinders where it has an adverse effect on wear and spark-plug life (2). 

In practice, the carbon-formation problem has been attacked chiefly by changes in combustor design and by control of fuel constituents and endpoint. However, a recent paper (2) states that use of dicyclopentadienyliron (ferrocene) as an additive drastically reduces or eliminates jet-fuel carbon deposits. 

There are many other shapes possible for complexes. The simplest are linear, with coordination number 2. An example is dimethylmercury(O), [Hg(CH3)2] (5), which is a toxic compound formed by bacterial action on aqueous solutions of Hg2+ ions. Coordination numbers of up to 12 are found for members of the f block, but they are rare in the d block. One interesting type of d-metal compound in which the coordination number is formally only 2 but there are 10 links between the ligands and the central metal ion is ferrocene, dicyclopentadienyliron(O), [Fe(C5H5)2] (6). Ferrocene is an aptly named sandwich compound, with the two cyclopentadienyl ligands the bread and the metal atom the filling. The formal name for a sandwich compound is a metallocene. 

Since the discovery of dicyclopentadienyliron (ferrocene) in 1951112 an immense body of literature has appeared concerning the chemistry of ferrocenes and related compounds. Although a large number of reviews3 have appeared, they have given only brief treatment to ferrocenes containing heterocyclic systems. It is the purpose of this review to report on those ferrocenes which contain heterocyclic systems either fused to the ferrocene or as a substituent on the ferrocene. 

Yeary RA (1969) Chronic toxicity of dicyclopentadienyliron (ferrocene) in dogs. Toxicol Appl Pharmacol 15 666-676... 

In Fe(C5H5)2 (also written sometimes as Fe(cp)2 and known as dicyclopentadienyliron or ferrocene), the C5H5- rings behave as six-electron donors. Because Fe2+ has 24 electrons,... 

An important cdass of organo-metallic compounds are the so-called metal-sandwich compounds. These csompounds have the formula (C H,),M and consist of a transition metal atom M sandwiched symmetrically between two paraUel oarbocycUo ring systems, e.g, ferrocene, or, to give it its proper name, dicyclopentadienyliron [(C,H,) Fe], and... 

Yeary, R. A., Chronic Toxicity of Dicyclopentadienyliron (Ferrocene) in Dogs , Toxicol. Appl. Pharmacol. IS (1969) 666-667. 

However, under certain conditions C-H activation can also be facile and favorable with first-row transition metals. To illustrate this point, just two examples are given here. In 1952, Miller, Tebboth and Tremaine reported the formation of a very stable volatile complex, when cyclopentadiene was passed over reduced iron at 300 The product, dicyclopentadienyliron (later called ferrocene) obviously is a C H activation product of cyclopentadiene (Eq. 1). Much later, Timms was able to show that the same reaction could also be brought about at a temperature as low as —196 °C. There are many examples of similar reactions in the literature. They... 

Dunitz JD, Orgel LE (1953) Dicyclopentadienyliron a molecular sandwich. Nature 171 121-122... 

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