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.[2]
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.[3][4]
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):
↑Organic Syntheses via Metal Carbonyls Volume 1. NY: Wiley Interscience. 1968.
↑Bird, C. W. (1962). "Synthesis of Organic Compounds by Direct Carbonylation Reactions Using Metal Carbonyls". Chemical Reviews62 (4): 283–302. doi:10.1021/cr60218a001.
↑Giordano, Roberto; Sappa, Enrico; Cauzzi, Daniele; Predieri, Giovanni; Tiripicchio, Antonio (1996). "Reactions of the 'ferrole' complex [Fe2(CO)6(C2Et2)2] with group 15 donor ligands and with alkynes. Stepwise formation and disengagement of tropones. Crystal and molecular structure of [Fe2(CO)5{(CEt)2 CO(CEt)2 CHCPH}]". Journal of Organometallic Chemistry511 (1–2): 263–271. doi:10.1016/0022-328X(95)05936-J.