Simple Route to Li‐ or Zn‐Metalated η⁵‐Cyclopentadienyliron‐Olefin Complexes

Abstract

Some new reactions of ferrocene with lithium and olefins involve only replacement of a C5H5 ligand. The product, e.g.(1). DME and (1). TMEDA, can be metalated with ZnCl2 or CdCl2 and transformed into trinuclear complexes with olefinic ligands bonded to iron, such as(2). Reaction of (1) and trityl chloride produces the monomeric radical CpFe(COD)•.

Mixed AggregAte (MAA): A Single Concept for All Dipolar Organometallic Aggregates. 2. Syntheses and Reactivities of Homo/HeteroMAAs

“…The ability of highly reduced Mg,Fe clusters to allow cross-couplings was shown using the low-valent Fe complex [Li(TMEDA) 2 ][(C 2 H 4 ) 4 Fe], described by Jonas and co-workers, to perform reactions between aryl Grignard reagents and alkyl halides . Low-valent Fe complexes cannot be considered any more for cross-couplings of aryl Grignard reagents with aryl halides such as π-electron-deficient halo substrates. , …”

16-Electron Nickel(0)-Olefin Complexes in Low-Temperature C(sp2)–C(sp3) Kumada Cross-Couplings

“…Despite the wealth of literature involving the use of electron-donating ligands in Ni-catalyzed reactions, much less is known about an alternative electronic situation on the catalyst, where the metal center is highly reduced and the additional charge is stabilized through its ligands (Figure C). This situation is favored when certain π-accepting functionalities such as olefins are acting as ancillary ligands for the Ni center . Whereas σ-electron-donating ligands favor oxidative addition, π-accepting ligands such as olefins offer opportunities for tuning other steps of the catalytic cycle .…”

The 18-Electron, Metal−Metal-Bonded Dimers [η5-C5Ph5Fe(CO)2]2 and [η5-C5Ph4(p-tolyl)Fe(CO)2]2: Their Proclivity To Undergo Spontaneous, Thermal Homolysis to the Corresponding 17-Electron Monomers

“…In an analogous investigation of novel C-C bond forming reactions, Sen et al found that [CpFe(COD)] -(COD ) 1,5-cyclooctadiene) undergoes a one-electron oxidation with benzyl halide to form the neutral 17-electron species CpFe(COD), 24d which then couples with the benzyl radical to form CpFe(COD)CH 2 Ph although CpFe(COD) has been briefly claimed to be reasonably persistent at room temperature. 25 Certainly the sterically hindered compounds Cp*Fe(C 2 H 4 ) 2 and Cp*Fe-(COD), while substitutionally labile, are thermally very well behaved. 24d Finally, the 17-electron Cp*Fe(dppe) (dppe ) 1,2-bis(diphenylphosphino)ethane), prepared via reduction of Cp*Fe(dppe)(OSO 2 CF 3 ), is sufficiently stable that an X-ray crystal structure has been reported.…”

“…In an analogous investigation of novel C−C bond forming reactions, Sen et al . found that [CpFe(COD)] - (COD = 1,5-cyclooctadiene) undergoes a one-electron oxidation with benzyl halide to form the neutral 17-electron species CpFe(COD),24d which then couples with the benzyl radical to form CpFe(COD)CH 2 Ph although CpFe(COD) has been briefly claimed to be reasonably persistent at room temperature 24d.…”