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 + 6 CO
An unusual route to ferroles involves treatment of Collman's reagent with trimethylsilyl chloride (tms = (CH3)3Si):
- 2 Na2Fe(CO)4 + 4 tmsCl → Fe2(CO)6C4(Otms)4 + 2 CO + 4 NaCl (warning: unbalanced reaction !)
Reactions
Some ferroles react with tertiary phosphines to give the substituted flyover complex Fe2(CO)5(PR3)(C4R4CO).
References
- Dettlaf, Gerd; Weiss, Erwin (1976). "Kristallstruktur, H-NMR- und Massenspektrum von Tricarbonylferracyclopentadien-tricarbonyleisen, C4H4Fe2(CO)6". Journal of Organometallic Chemistry. 108 (2): 213–223. doi:10.1016/S0022-328X(00)82143-9.
- Fehlhammer, W.P.; Stolzenberg, H. (1982). "Dinuclear Iron Compounds with Hydrocarbon Ligands". In Geoffrey Wilkinson; F. Gordon A. Stone; Edward W. Abel (eds.). Comprehensive Organometallic Chemistry. pp. 513–613. doi:10.1016/B978-008046518-0.00051-9. ISBN 9780080465180.
- Piero Pino; Irving Wender, eds. (1968). Organic Syntheses via Metal Carbonyls Volume 1. NY: Wiley Interscience.
- Bird, C. W. (1962). "Synthesis of Organic Compounds by Direct Carbonylation Reactions Using Metal Carbonyls". Chemical Reviews. 62 (4): 283–302. doi:10.1021/cr60218a001.
- Giordano, Roberto; Sappa, Enrico; Cauzzi, Daniele; Predieri, Giovanni; Tiripicchio, Antonio (1996). "Reactions of the 'ferrole' complex with group 15 donor ligands and with alkynes. Stepwise formation and disengagement of tropones. Crystal and molecular structure of ". Journal of Organometallic Chemistry. 511 (1–2): 263–271. doi:10.1016/0022-328X(95)05936-J.
- Fagan, Paul J. (1995). "Dinuclear Iron Compounds with Hydrocarbon Ligands". Comprehensive Organometallic Chemistry II. pp. 231–258. doi:10.1016/B978-008046519-7.00058-7. ISBN 9780080465197.