Ferrocenium Hexafluorophosphate

• CAS: 11077-24-0
• Catalog Number: ACM11077240
• Category: Promotional Products
• Molecular Weight: 331
• Molecular Formula: C10H10F6FeP
• Synonyms: cyclopentane;iron;hexafluorophosphate
• SMILES: C1=C[CH]C=C1.C1=C[CH]C=C1.F[P-](F)(F)(F)(F)F.[Fe]
• InChI: InChI=1S/2C5H5.F6P.Fe/c2*1-2-4-5-3-1;1-7(2,3,4,5)6;/h2*1-5H;/q;-1
• InChI Key: PCJFEGIXYOQEQD-UHFFFAOYSA-N
• Appearance: solid
• Storage: room temperature
• Complexity: 101
• Covalently-Bonded Unit Count: 4
• Defined Atom Stereocenter Count: 0
• Exact Mass: 330.977367
• Heavy Atom Count: 18
• Hydrogen Bond Acceptor Count: 7
• Hydrogen Bond Donor Count: 0
• Monoisotopic Mass: 330.977367
• Rotatable Bond Count: 0
• Topological Polar Surface Area: 0 Ų

Case Study

Ferrocenium Hexafluorophosphate-Induced Electropolymerization for Nanofibrillar Pani-PVS Film Development in Biosensor Fabrication

Ndangili P. M, et al. Electrochimica Acta, 2010, 55(14), 4267-4273.

Ferrocenium hexafluorophosphate (FcPF₆) was employed as a key oxidizing agent to direct the nanofibrillar electropolymerization of polyaniline-polyvinyl sulfonate (Pani-PVS) films for biosensor applications. Electropolymerization was conducted on both glassy carbon electrodes (GCE) and screen-printed carbon electrodes (SPCE) in a 1 M HCl acidic medium, using a working solution containing 0.05 M FcPF₆, 0.2 M aniline, and polyvinyl sulfonate (PVS). The solution was degassed with argon for 8 minutes, and potential cycling was performed from -100 mV to +1000 mV at 100 mV s⁻¹ for 20 cycles. FcPF₆ played a critical role in shifting the morphology of the film from micron-sized cauliflower clusters to uniformly distributed 100 nm nanofibrils, as confirmed by SEM imaging.
The resulting Pani-PVS films provided a biocompatible matrix for horseradish peroxidase (HRP) immobilization via glutaraldehyde crosslinking in the presence of bovine serum albumin (BSA). The modified electrode demonstrated fast amperometric response (within 5 s) to hydrogen peroxide with a detection limit of 30 µM and linearity up to 2 mM. This underscores FcPF₆'s pivotal role in engineering conductive nanostructures for high-performance biosensors.

Ferrocenium Hexafluorophosphate-Catalyzed Etherification of Propargylic Alcohols via Single Electron Transfer Pathways

Queensen M. J, et al. Journal of Molecular Catalysis A: Chemical, 2015, 407, 221-229.

Ferrocenium hexafluorophosphate ([FeCp₂]PF₆) has emerged as an efficient, cost-effective single-electron oxidant for the mild etherification of propargylic alcohols. In a representative protocol, tertiary propargylic alcohols (both mixed aromatic-aliphatic and purely aromatic) were reacted with equimolar quantities of primary or secondary alcohols in dichloromethane (CH₂Cl₂) at 40 °C using 3 mol% [FeCp₂]PF₆. The reaction proceeds without the need for additional reagents or additives and completes within 5 hours to 3 days depending on substrate reactivity.
Product isolation yielded propargylic ethers in 90-20% yields, with mixed aromatic-aliphatic alcohols affording higher conversions. In contrast, purely aromatic substrates underwent partial Meyer-Schuster rearrangement, limiting yield due to competitive aldehyde formation. Time-course monitoring confirmed this side reaction pathway.

Phosphorus Nucleophile-Responsive, Cp-Ring Functionalizing and Half-Sandwich Complex-Forming Properties of Ferrocenium Hexafluorophosphate

Chamkin, A. A., Krivykh, V. V., Kreindlin, A. Z., Dolgushin, F. M., & Ustynyuk, N. A. European Journal of Inorganic Chemistry, 2021, 2021(16): 1601-1610.

The chemical composition, reaction characteristics and product-selective properties of ferrocenium hexafluorophosphate ([Cp2 Fe]PF6 ) were studied using nuclear magnetic resonance (NMR) spectroscopy, X-ray diffraction (XRD), density functional theory (DFT) calculations, and in vitro organometallic reaction assays. Ferrocenium hexafluorophosphate is a cationic metallocene salt with a deep blue color, consisting of the ferrocenium cation ([Cp2 Fe]+) and hexafluorophosphate anion (PF6- ). The ferrocenium cation features two cyclopentadienyl (Cp) rings coordinated to a central Fe(III) ion, serving as a key redox-active center in organometallic reactions.
Ferrocenium hexafluorophosphate exhibited significant phosphorus nucleophile-responsive activity: in dichloromethane at room temperature, it reacted with diverse POR nucleophiles (phosphites, phosphonites, phosphinites) to produce two distinct types of products, governed by the Tolman Electronic Parameter (TEP) of the nucleophile. For nucleophiles with TEP < 2070 cm⁻¹ (e.g., iPr2 P(OMe), iPr2 P(OEt)), it underwent Cp-ring CH functionalization to form ferrocenylphosphonium salts [CpFe(C5 H4 PR3 )]PF6 with high yields (75-77%). For nucleophiles with TEP between 2073-2080 cm⁻¹ (e.g., P(OMe)3 , P(OEt)3 , PhP(OMe)2 ), it underwent Cp-ring replacement to form half-sandwich complexes [CpFe(PR3 )3 ]PF6 (yields 28-70%). For nucleophiles with TEP between 2070-2073 cm⁻¹ (e.g., Ph2 P(OMe), Ph2 P(OEt)), mixtures of both products were obtained. Additionally, the reaction mechanism was clarified via DFT calculations (M06-L/6-311++G(d,p) level): the initial step involves exo-addition of the P nucleophile to the Cp ring to form a 17-electron intermediate, followed by either deprotonation (for CH functionalization) or sequential P donor additions and Cp ring elimination (for half-sandwich complex formation), with the final redox step involving ferrocenium as an oxidizer to form ferrocene as a byproduct. These studies demonstrate that ferrocenium hexafluorophosphate possesses significant phosphorus nucleophile-responsive, Cp-ring functionalizing, and half-sandwich complex-forming properties.
The in vitro reaction and product-selective effects were investigated by reacting ferrocenium hexafluorophosphate with different POR nucleophiles (1.1-4.4 equivalents) in dichloromethane, monitoring reaction completion via color change from deep blue to orange. Products were characterized by 1H and 31P{1H} NMR spectroscopy, XRD (for crystal structures of [CpFe(C5 H4 PPh2 (OEt))]PF6 and [CpFe(PPh2 (OEt))3 ]BF4 ), and elemental analysis. DFT calculations were used to determine Gibbs free energy changes and activation energies for key reaction steps, confirming the role of 17-electron and 19-electron intermediates. The results verified that TEP is a reliable predictor of reaction outcome, with π-acceptor nucleophiles stabilizing 19-electron intermediates to favor half-sandwich complex formation.

Ferrocenylphosphonium Salt-Forming and Oxidative Nucleophilic Substitution Properties of Ferrocenium Hexafluorophosphate

Chamkin, A. A., Krivykh, V. V., Shtel'tser, N. A., Semeikin, O. V., Dolgushin, F. M., & Ustynyuk, N. A. Russian Chemical Bulletin, International Edition, 2019, 68(3): 532-539.

The chemical composition, reaction mechanism and product-forming properties of ferrocenium hexafluorophosphate ([Cp2 Fe]PF6 ) were studied using nuclear magnetic resonance (¹H, ¹³C, ³¹P{¹H} NMR) spectroscopy, X-ray diffraction (XRD), density functional theory (DFT) calculations, and in vitro organometallic reaction assays. Ferrocenium hexafluorophosphate is a blue cationic metallocene salt composed of the ferrocenium cation ([Cp2 Fe]+) and hexafluorophosphate anion (PF6- ), with the central Fe(III) ion coordinated by two cyclopentadienyl (Cp) rings, serving as a key redox-active substrate in phosphination reactions.
Ferrocenium hexafluorophosphate exhibited significant aminophosphine-phosphinating activity: in dichloromethane at room temperature, it reacted with a series of aminophosphines (P(NEt2 )3 , PhP(NEt2 )2 , Ph2 P(NEt2 ), CyP(NEt2 )2 , iPr2 P(NEt2 )) to form ferrocenylphosphonium salts [CpFe(C5 H4 PRR'R'')]PF6 (yields 16-47%), along with equimolar ferrocene and aminophosphine conjugate acid [HPRR'R'']PF6 as byproducts. The reaction followed an oxidative nucleophilic substitution mechanism, confirmed by DFT calculations (M06-L/6-311++G(d,p) level): 1) nucleophilic exo-addition of aminophosphine to the Cp ring forming a 17-electron radical cation intermediate; 2) oxidation of this intermediate by excess ferrocenium to generate a dicationic η4-phosphocyclopentadiene complex with an agostic Csp3 -H→Fe bond; 3) deprotonation of the agostic bond by the starting aminophosphine to form the final phosphonium salt. Additionally, the resulting ferrocenylphosphonium salts showed high chemical stability: they were resistant to alcoholysis (reflux in methanol for 3 h) and did not react with carbon disulfide (20°C for 2 days), attributed to the positively charged phosphorus atom inhibiting electrophilic attacks. These studies demonstrate that ferrocenium hexafluorophosphate possesses significant aminophosphine-phosphinating, ferrocenylphosphonium salt-forming, and oxidative nucleophilic substitution properties.
The in vitro reaction and mechanism validation were investigated by reacting ferrocenium hexafluorophosphate with 1.15-2.3 equivalents of aminophosphines, monitoring completion via color change from blue to orange. Products were characterized by NMR spectroscopy (confirming monosubstituted ferrocene structure with characteristic ¹H NMR signals at δ 4-5), XRD (for [CpFe(C5 H4 PPh(NEt2 )2 )]PF6 , confirming P-Cp bond length 1.777 Å and eclipsed Cp ring orientation), and elemental analysis. DFT calculations quantified Gibbs free energy changes and activation barriers for key steps, verifying the role of agostic interactions in facilitating deprotonation. The results verified that the reaction stoichiometry follows 2:2:1 (ferrocenium:aminophosphine:ferrocenylphosphonium salt), with aminophosphines acting as both nucleophiles and deprotonating agents.