Electrochemical Reduction Mechanism of [(η⁵-C₅H₅)Fe(dppf)(CO)]⁺ (dppf = 1,1′-Bis(diphenylphosphino)ferrocene)

Abstract

The complex [CpFe(dppf)(CO)][B(Ar F ) 4 ] [1][B-(Ar F ) 4 ] (Cp = cyclopentadienyl, dppf = 1,1′-bis-(diphenylphosphino)ferrocene, and [B(Ar F ) 4 ] − = tetrakis[3,5bis(trifluoromethyl)phenyl]borate) was made by removal of one carbonyl ligand from the dicarbonyl complex [CpFe(CO) 2 (κ 1dppf)]I and exchange of the I − for [B(Ar F ) 4 ] − that allowed for electrochemical investigations. The cyclic voltammogram of [1] + showed a reversible anodic process due to oxidation of the ferrocenediyl moiety of the dppf ligand. A quasi-reversible cathodic process was also observed, and this reduction occurred at the CpFe moiety, as determined by variable-temperature (+22 and −30 °C) IR spectroelectrochemistry (SEC) and further supported by DFT calculations. This reduction event resulted in the formation of the two possible dimers [Cp 2 Fe 2 (μ-CO) 2 (μ-dppf)] and [Cp 2 Fe 2 (CO) 2 (μ-dppf)] along with deligation of one dppf ligand.

(Spectro)Electrochemistry of 3‐(Pyrid‐2‐yl)‐s‐Tetrazine‐ and 1,2‐ (Dihydro)pyridazine Tricarbonylrhenium(I)chloride

“…The UV‐vis‐NIR SEC spectra for [1H 2 Fc] 0/+ (Figure 5) show two main MLCT features (Table 3), that were red shifted upon oxidation, and a weak band at 630 nm appears. This weak band is consistent with ferrocenium [34–38] . These features are also described by TD‐DFT (Figure S20).…”

“…This weak band is consistent with ferrocenium. [34][35][36][37][38] These features are also described by TD-DFT (Figure S20). The UV-vis-NIR SEC [1H 2 Fc] 0/ À 1 resulted in the MLCT band at 443 nm to decrease in intensity and the appearance of a new blue shifted band at 372 nm and a weak band at 540 nm to appear.…”

Amine-catalyzed substitution in CpFe(CO)2I by phosphine and bisphosphine ligands

“…3). 26 Our results indicate that amines, especially DIPA, substantially accelerate the reaction of complex 1 with aromatic phosphines and direct it toward the substitution of the iodide ligand with phosphine.…”

Organobimetallic Nickel‐Iron Complexes, Valence Tautomer or Charge Localized Ferrocene Ligands Upon Oxidation

“…The appearance of low energy band at 650 nm (0.58 mM À 1 cm À 1 ) is typical the ferrocenium ion. For example, the ferrocenium found in [CpFe(CO)(dppf)] 2 + showed an absorption at 630 nm (0.17 mM À 1 cm À 1 ) [29] and ferrocenium has an absorption band at 617 nm (0.42 mM À 1 cm À 1 ). [30][31] The larger extinction coefficient observed in [1] 2 + was attributed to an additional IVCT band between the Ni II !Fe III predicted by TD DFT.…”