One-electron oxidation and protonation of diferrocenylphenylphosphine
Corina Stoian


A
B
Abstract
The one-electron oxidation and protonation of diferrocenylphenylphosphine (Fc2PhP) leads to the formation of two distinct, stable cationic phosphorus species, namely the radical cation [Fc2PhP][B(C6F5)4] and the phosphonium ion [Fc2PhPH][B(C6F5)4]. Although their solid-state structures are remarkably similar, the bathochromic shift in the UV-Vis absorption spectrum of the radical cation, signals with distinct multiplicities in the 31P NMR spectra, as well as contrasting quadrupole splitting values in the 57Fe Mößbauer spectra, elucidated the differences between the two cations.
Keywords: diferrocenylphenylphosphine, mixed-valency, one-electron oxidation, protonation, radical cation.
References
1 Straube A, Useini L, Hey-Hawkins E. Multi-ferrocene-based ligands: from design to applications. Chem Rev 2025; 125: 3007-3058.
| Crossref | Google Scholar | PubMed |
2 Santi S, Bisello A, Cardena R, Donoli A. Key multi(ferrocenyl) complexes in the interplay between electronic coupling and electrostatic interaction. Dalton Trans 2015; 44: 5234-5257.
| Crossref | Google Scholar | PubMed |
3 Köring L, Stepen A, Birenheide B, Barth S, Leskov M, Schoch R, Krämer F, Breher F, Paradies J. Boron-centered Lewis superacid through redox-active ligands: application in C−F and S−F bond activation. Angew Chem Int Ed 2023; 62: e202216959.
| Google Scholar |
4 Sadow AD, Togni A. Enantioselective addition of secondary phosphines to methacrylonitrile: catalysis and mechanism. J Am Chem Soc 2005; 127: 17012-17024.
| Crossref | Google Scholar | PubMed |
5 Süssner M, Plenio H. Redox-switchable phase tags for recycling of homogeneous catalysts. Angew Chem Int Ed 2005; 44: 6885-6888.
| Crossref | Google Scholar | PubMed |
6 Delgado-Pena F, Talham DR, Cowan DO. Near-IR spectroscopic studies of mixed-valence di-, tri-, and tetraferrocene derivatives. J Organomet Chem 1983; 253: C43-C46.
| Crossref | Google Scholar |
7 Durfey DA, Kirss RU, Frommen C, Feighery W. Synthesis and Mossbauer spectroscopic studies of chemically oxidized ferrocenyl(phenyl)phosphines. Inorg Chem 2000; 39: 3506-3514.
| Crossref | Google Scholar | PubMed |
8 Barrière F, Kirss RU, Geiger WE. Anodic electrochemistry of multiferrocenyl phosphine and phosphine chalcogenide complexes in weakly nucleophilic electrolytes. Organometallics 2005; 24: 48-52.
| Crossref | Google Scholar |
9 Hu H, Ichiryu H, Nakajima K, Ogasawara M. Estimating effective steric and electronic impacts of a ferrocenyl group in organophosphines. ACS Omega 2021; 6: 5981-5989.
| Crossref | Google Scholar | PubMed |
10 Kotz JC, Nivert CL. Organometallic ligands: the preparation and properties of complexes of the ferrocenylphosphines. J Organomet Chem 1973; 52: 387-406.
| Crossref | Google Scholar |
11 Sollott GP, Mertwoy HE, Portnoy S, Snead JL. Unsymmetrical tertiary phosphines of ferrocene by Friedel–Crafts reactions. I. Ferrocenylphenylphosphines. J Org Chem 1963; 28: 1090-1092.
| Crossref | Google Scholar |
12 Das B, Makol A, Kundu S. Phosphorus radicals and radical ions. Dalton Trans 2022; 51: 12404-12426.
| Crossref | Google Scholar | PubMed |
13 Guillaneux D, Kagan HB. High yield synthesis of monosubstituted ferrocenes. J Org Chem 1995; 60: 2502-2505.
| Crossref | Google Scholar |
14 Miesel D, Hildebrandt A, Rüffer T, Schaarschmidt D, Lang H. Electron-transfer studies of trans-platinum bis (acetylide) complexes. Eur J Inorg Chem 2014; 2014: 5541-5553.
| Crossref | Google Scholar |
15 Pan X, Chen X, Li T, Li Y, Wang X. Isolation and X-ray crystal structures of triarylphosphine radical cations. J Am Chem Soc 2013; 135: 3414-3417.
| Crossref | Google Scholar | PubMed |
16 Dankert F, Muhm SP, Nandi C, Danés S, Mullassery S, Herbeck-Engel P, Morgenstern B, Weiss R, Salvador P, Munz D. Hexaphenyl-1,2-diphosphonium dication [Ph3P-PPh3]2+: superacid, superoxidant, or super reagent? J Am Chem Soc 2025; 147: 15369-15376.
| Crossref | Google Scholar | PubMed |
17 Jutzi P, Müller C, Stammler A, Stammler H-G. Synthesis, crystal structure, and application of the oxonium acid [H(OEt2)2]+[B(C6F5)4]−. Organometallics 2000; 19: 1442-1444.
| Crossref | Google Scholar |
18 Stoian C, Olaru M, Demeshko S, Fischer M, Mebs S, Hupf E, Beckmann J. Heavier diferrocenylpnictogenium ions. Chem Eur J 2025; 31: e202403555.
| Crossref | Google Scholar | PubMed |
19 Reiners M, Baabe D, Schweyen P, Freytag M, Jones PG, Walter MD. Teaching ferrocenium how to relax: a systematic study on spin–lattice relaxation processes in tert-butyl-substituted ferrocenium derivatives. Eur J Inorg Chem 2017; 2017: 388-400.
| Crossref | Google Scholar |
20 Malischewski M, Seppelt K, Sutter J, Heinemann FW, Dittrich B, Meyer K. Protonation of ferrocene: a low-temperature X-ray diffraction study of [Cp2FeH](PF6) reveals an iron-bound hydrido ligand. Angew Chem Int Ed 2017; 56: 13372-13376.
| Crossref | Google Scholar | PubMed |
21 Houlton A, Roberts RMG, Silver J, Drew MGB. Ferrocenyl ligands. Part 1. An analysis of the structures of substituted ferrocenylphosphines to aid in the understanding of the ligand bonding. The crystal and molecular structure of diferrocenylphenylphosphine. J Chem Soc, Dalton Trans [5] 1990; 1543-1547.
| Crossref | Google Scholar |
22 McNelis E, Blandino M. 657, A method for estimating tetrahedral bond angles. New J Chem 2001; 25: 772-774.
| Crossref | Google Scholar |
23 Jayatilaka D, Dittrich B. X-Ray structure refinement using aspherical atomic density functions obtained from quantum-mechanical calculations. Acta Cryst A 2008; 64: 383-393.
| Crossref | Google Scholar | PubMed |
24 Fugel M, Jayatilaka D, Hupf E, Overgaard J, Hathwar VR, Macchi P, Turner MJ, Howard J, Dolomanov OV, Puschmann H, Iversen BB, Bürgi H-B, Grabowsky S. Probing the accuracy and precision of Hirshfeld atom refinement with HARt interfaced with Olex2. IUCrJ 2018; 5: 32-44.
| Crossref | Google Scholar | PubMed |
25 Duvinage D, Puylaert P, Wieduwilt EK, Malaspina LA, Edwards AJ, Lork E, Mebs S, Hupf E, Grabowsky S, Beckmann J. Nickel and palladium complexes of a PP(O)P pincer ligand based upon a peri-substituted acenaphthyl scaffold and a secondary phosphine oxide. Inorg Chem 2022; 61: 8406-8418.
| Crossref | Google Scholar | PubMed |
26 Romanato P, Duttwyler S, Linden A, Baldridge KK, Siegel JS. Intramolecular halogen stabilization of silylium ions directs gearing dynamics. J Am Chem Soc 2010; 132: 7828-7829.
| Crossref | Google Scholar | PubMed |
27 Khan FST, Waldbusser AL, Carrasco MC, Pourhadi H, Hematian S. Synthetic, spectroscopic, structural, and electrochemical investigations of ferricenium derivatives with weakly coordinating anions: ion pairing, substituent, and solvent effects. Dalton Trans 2021; 50: 7433-7455.
| Crossref | Google Scholar | PubMed |
28 Fulmer GR, Miller AJM, Sherden NH, Gottlieb HE, Nudelman A, Stoltz BM, Bercaw JE, Goldberg KI. NMR Chemical shifts of trace impurities: common laboratory solvents, organics, and gases in deuterated solvents relevant to the organometallic chemist. Organometallics 2010; 29: 2176-2179.
| Crossref | Google Scholar |
29 Dolomanov OV, Bourhis LJ, Gildea RJ, Howard JAK, Puschmann H. OLEX2: a complete structure solution, refinement and analysis program. J Appl Cryst 2009; 42: 339-341.
| Crossref | Google Scholar |