Preparation and One-Electron Oxidation of Decabromoferrocene

Abstract

We report an improved synthesis as well as a spectroscopical, structural, and electrochemical characterization of decabromoferrocene (FeC 10 Br 10 ) and relevant side products. Oneelectron oxidation of decabromoferrocene (E 1/2 = 1.095 V vs FeCp 2 0/+ ) was achieved by AsF 5 in liquid SO 2 . The crystal structure of decabromoferrocenium hexafluoroarsenate, [FeC 10 Br 10 ][AsF 6 ], represents the first example of an isolated and structurally characterized perhalogenated ferrocenium salt.

Isolation and crystal and molecular structures of [(C5H2Br3)2Fe], [(C5HBr4)2Fe] and [(C5Br5)(C5Br4HgBr)Fe]

“…4). The C10-Hg1-Br10 bond deviates slightly from being linear while the iron-centroid distances are significantly shorter in 8, which is quite usual when comparing ferrocenes with their oxidized counterparts (Rupf et al, 2022). For all three compounds, an analysis with PLATON showed no residual solvent-accessible voids (Spek, 2020).…”

“…Relatively rarely studied were metal-containing systems (Brammer et al, 2008), in particular, organometallic systems have so far been restricted to a few metal carbonyls, ruthenium-complexed aryl iodides (Kelly & Holman, 2022) and one study on 1,1 0 -dihaloferrocenes (Shimizu & Ferreira da Silva, 2018). Our group has been working on polyhalogenated metallocenes for quite a while (Su ¨nkel & Motz, 1988;Su ¨nkel & Hofmann, 1992;Su ¨nkel et al, 1994Su ¨nkel et al, , 2015Su ¨nkel & Bernhartzeder, 2011), and some very recent reports on the synthesis and crystal structure determinations of [(C 5 H n Br 5-n )(C 5 H 2 Br 3 )Fe] (n = 1 or 2; Butler et al, 2021;Butler, 2021) and [(C 5 H n Br 5-n )(C 5 Br 5 )Fe] (n = 0 or 1; Rupf et al, 2022) prompted us to report on our synthetic and crystallographic studies of polybromoferrocenes. A special focus is made on the occurrence of halogen and hydrogen bonding in these systems.…”

Synthesis and Spectroscopic Characterization of the Four Complete Series [(C5XnH5‐n)Fe(CO)2R] (X= Cl, Br; R= Me, Ph; n= 1–5). Molecular and Crystal Structures of [(C5X5)Fe(CO)2R]

“…In this compound the average C−Cl distance is 1.702(4) Å and the iron‐centroid distance is 1.648 Å. Two different studies describe crystal structures containing a [Fe(C 5 Br 5 )] unit: one is about pentabromoferrocene, [19d] the other on nona‐ and decabromoferrocene [24] . In these compounds, the C−Br distances are around 1.869 Å, while the iron centroid distance is in pentabromoferrocene significantly shorter than in the decabromo compound (1.609(3) Å vs. 1.644(1) Å).…”

“…Two different studies describe crystal structures containing a [Fe(C 5 Br 5 )] unit: one is about pentabromoferrocene, [19d] the other on nona-and decabromoferrocene. [24] In these compounds, the CÀ Br distances are around 1.869 Å, while the iron centroid distance is in pentabromoferrocene significantly shorter than in the decabromo compound (1.609(3) Å vs. 1.644(1) Å). These distances show, that the CÀ X distances do not depend on the nature of the coordinated metal fragment, whileÀ not unexpectedlyÀ the iron centroid distance does.…”

A Decacationic Ferrocene-Based Metallostar

“…[25] In 2021 we reported a simple perfunctionalization approach by treatment of ferrocene with mercury(II) carboxylates to obtain FeC10(HgX)10 (X = O2CC3H7, O2CCF3, O2CCCl3) in multigram scale. [26] Although these compounds offer relatively weak Hg-C bonds allowing transmetallation [27,28] and electrophilic substitution reactions [29,30] they are chemically inert towards air and strong Brønsted acids (e.g. CF3CO2H pKa = −2.7 estimated in H2O [31] ) caused by the low polarity of the Hg-C bond as well as the low Lewis acidity of the R-Hg-X units to form adducts with increased coordination number.…”