In organoiron chemistry, a ferrole is a type of diiron complex containing the (OC)3FeC4R4 heterocycle that is pi-bonded to a Fe(CO)3 group. These compounds have Fe-Fe bonds (ca. 252 pm) and semi-bridging CO ligands (Fe-C distances = 178, 251 pm). They are typically air-stable, soluble in nonpolar solvents, and red-orange in color. Synthesis Ferroles typically arise by the reaction of alkynes with iron carbonyls. Such reactions are known to generate many products, e.g. complexes of cyclopentadienones and para-quinones.
Another route involves the desulfurization of thiophenes (SC4R4) by iron carbonyls, shown in the following idealized equation: Fe3(CO)12 + SC4R4 → Fe2(CO)6C4R4 + FeS + 6CO
An unusual route to ferroles involves treatment of Collman's reagent with trimethylsilyl chloride (tms = (CH3)3Si): 2Na2Fe(CO)4 + 4tmsCl → Fe2(CO)6C4(Otms)4 + 2CO + 4NaCl
Reactions Some ferroles react with tertiary phosphines to give the substituted flyover complex Fe2(CO)5(PR3)(C4R4CO).
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