Within only five minutes at 20°C bimetallic fulvalene complexes 1 undergo intramolecular disproportionation in the presence of PMe3 or P(OMe)3 when electron‐reservoir complexes of the type [FeICp(arene)] serve as catalysts. MI = Mo, W, Fe, Ru; M2 = Mo, W; n = 2, 3; m = 3; arene = C6H6, C6Me6. The heterodinuclear complexes react with regioselectivity.

The C-0 bond of Fe(q5-C5H5)+ complexes of aryl ethers is cleaved smoothly by reaction of ButOK in THF or KOH in DME, yielding n-phenate complexes; transetherification can also be achieved in situ at room temperature.

The bi-sandwich complex [Fe2Fv(C6H6)2]2+(PF6 -)2 (1 2+; Fv = μ2-η5:η5-fulvalenyl, unless noted otherwise) synthesized from biferrocene, was photolyzed with visible light in acetonitrile in the presence of 1,2-bis(diphenylphosphino)ethane (dppe) or bis(diphenylphosphino)methane (dppm) at −15 °C to give [Fe2Fv(dppe)2(NCMe)2]2+(PF6 -)2 (2a 2+) or [Fe2Fv(dppm)2(NCMe)2]2+(PF6 -)2 (2b 2+). The complexes 2a 2+ and 2b 2+ reacted in refluxing 1,2-dichloroethane with CO to give [Fe2Fv(dppe)2(CO)2]2+(PF6 -)2 (3a 2+) and [Fe2Fv(dppm)2(CO)2]2+(PF6 -)2 (3b 2+), and 2a 2+ reacted similarly with PMe3 to give [Fe2Fv(dppe)2(PMe3)]2+(PF6 -)2 (4 2+). The direduced 38-electron (38e) complex 1 reacted at −15 °C with 1 atm of CO to give [Fe2(μ2-η4:η4-Fv)(CO)6] (7) and with PMe3 to give [Fe2Fv(PMe3)4] (9). When Na+PF6 - was present in stoichiometric amounts in THF, these reactions followed a different course and Na+PF6 - induced electron transfer (disproportionation) by irreversibly dislocating ion pairs:  the reaction of 1 with 1 atm of CO gave [Fe(η5-Fv)(η6-C6H6), Na+PF6 -] (5), and that with PMe3 gave [Fe2Fv(PMe3)6]2+(PF6 -)2 (8 2+) and the known complex [Fe(PMe3)4] (10). The cyclic voltammograms (CV) of 2a 2+ and 2b 2+ contain irreversible oxidation and reduction waves, but the CVs of 3a 2+ and 3b 2+ showed two close reversible monoelectronic reduction waves (no oxidation wave). The CVs of the hexaphosphine complexes indicated partially or fully irreversible reduction waves, respectively, but two reversible waves at +0.71 and +0.95 V for 4 2+ and +0.70 and +1.08 V for 8 2+ (vs SCE, Pt, DMF, 0.1 M n-Bu4NBF4 −30 °C). The bielectronic reduction of 2a 2+ and the bielectronic oxidation of 4 2+ and 8 2+ using redox reagents led to decomposition, but the monoelectronic oxidation of 4 2+ and 8 2+ using (p-Br-C6H4)3N+SbCl6 - in CH2Cl2 gave the stable mixed-valence trications 4 3+ and 8 3+ , for which the Mössbauer spectra showed delocalized average valency on the Mössbauer time scale. These studies have opened the route to a variety of mono- and diiron fulvalenyl organometallic compounds, confirming the great importance of the presence of Na+PF6 -. This salt can change reaction pathways and, in particular, induce electron-transfer reactions, underlining the extraordinary electronic flexibility of the fulvalenyl ligand and its ability to transfer the electron flow between two metal centers.

The redox chemistry of [WM(f~lvalene)(CO)~], M = Fe (1) and Ru (2) allows the specific redox properties of each metal centre to be distinguished.

C 5 (CH 2 Ph) 5 H, C 5 Bz 5 H, 1, the precursor of the useful C 5 Bz 5 ligand that was introduced by Rausch, has been synthesized in 85% yield, a slight improvement over the 62% yield very recently reported by Rausch. [Fe(C 5 Bz 5 )(CO) 2 ], 2, also reported by Rausch, could be obtained in 72% yield as the only product of the reaction between 1 and [Fe(CO) 5 ] at 90 °C for 4 days. Reaction of 1 with Br 2 gives [Fe(C 5 Bz 5 )(CO) 2 Br], 3, in 84% yield. Photolysis of 3 in THF using visible light in the presence of Na + S 2 CNMe 2 -(Na + dtc -) gives a 73% yield of [Fe(C 5 Bz 5 )(CO)(η 2 -dtc)], 4, whose oxidation by [FeCp 2 ] + PF 6 -gives the 17electron complex [Fe III (C 5 Bz 5 )(η 2 -dtc)(NCMe)] + PF 6 -, 5, the precursor of [Fe IV Cp*(η 2 -dtc) 2 ] + -PF 6 -, 7. Cyclic voltammetry studies of the C 5 Bz 5 -iron complexes show that the electronic properties of C 5 Bz 5 are intermediate between those of C 5 H 5 (Cp) and C 5 Me 5 (Cp*) and that C 5 Bz 5 destabilizes paramagnetic iron complexes as opposed to the stabilizing property of Cp*.

Bei 20°C in nur fünf Minuten gelingt die intramolekulare Disproportionierung von Dimetallkomplexen 1 mit Fulvalenbrücke in Gegenwart von PMe3 oder P(OMe)3, wenn Elektronenreservoirkomplexe des Typs [Fe1Cp(Aren)] als Katalysatoren dienen. M1 = Mo, W, Fe, Ru; M2 = Mo, W; n = 2,3; m = 3; Aren = C6H6, C6Me6. Die Heterozweikernkomplexe reagieren dabei regioselektiv.magnified image

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Heterolytic C-O Cleavage in Arylethers Activated by (Fe(η5-C5H5))+.-Transetherification of phenolethers can be achieved via the title complexes at room temperature. -(MOULINES, F.; DJAKOVITCH, L.; DELVILLE-DESBOIS, M.-H.; ROBERT, F.; GOUZERH, P.; ASTRUC, D.; J.