Ferrocene Dicyclopentadienyliron

Ferrocene 450 may be sulfonated by treatment with concentrated sulfiiric acid in acetic anhydride and it was later found that chlorosulfonic acid in acetic anhydride was a more convenient reagent. The acetic anhydride was used to minimize the concomitant oxidation of the substrate by chlorosulfonic acid. Depending on the ratio of reagent to substrate the product is either ferrocene mono- or disulfonic acid. Sequential treatment of ferrocene with chlorosulfonic acid and phosphorus trichloride in ether affords ferrocene monosulfonyl chloride, and the latter was successfully converted into several ferrocene sulfonamides.  

Ferrocenecarboxylic acid, the methyl ester and acetylferrocene were all sulfonated by sulfur trioxide-dioxan in the unsubstituted cyclopentadienyl ring this orientation of sulfonation would be anticipated since all the substituents are electron-withdrawing moieties. 

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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... 

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. 

Ferrocene (dicyclopentadienyliron(II))(CpFe)(Cp = h -cyclopentadienyl) (5.1) easily forms electron-donor acceptor (EDA) complexes with polyhalogen... 

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. 

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... 

An example of this latter form of achievement was the preparation and elucidation of the structure of dicyclopentadienyliron (ferrocene), diben-zenechromium iodide, and olefin metal 7r-complexes, which provided an introduction to a new type of chemical bond, the metal 7i-complex bond. 

Ferrocene is readily oxidized to the dicyclopentadienyliron(III) cation (ferricinium, also called ferrocenium or ferricenium) which is blue or green in dilute solution but blood red in concentrated solution. In the presence of an oxidizing agent such as FeClj the following reaction occurs [2269] ... 

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