Iron Complexes of 4,5-Bis(diorganophosphinomethyl)acridine Ligands

• Verfasst von: Roca Jungfer, Maximilian [VerfasserIn]
• Verfasst von: Rominger, Frank [VerfasserIn]
• Verfasst von: Oeser, Thomas [VerfasserIn]
• Verfasst von: Buchsteiner, Emilia [VerfasserIn]
• Verfasst von: Hashmi, A. Stephen K. [VerfasserIn]
• Verfasst von: Schaub, Thomas [VerfasserIn]
• Titel: Iron Complexes of 4,5-Bis(diorganophosphinomethyl)acridine Ligands
• Verf.angabe: Maximilian Roca Jungfer, Frank Rominger, Thomas Oeser, Emilia Götz, A. Stephen K. Hashmi, and Thomas Schaub
• Jahr: 2024
• Umfang: 14 S.
• Illustrationen: Illustrationen
• Fussnoten: Online veröffentlicht: 26. September 2024 ; Gesehen am 14.03.2025
• Titel Quelle: Enthalten in: Inorganic chemistry
• Ort Quelle: Washington, DC : American Chemical Society, 1962
• Jahr Quelle: 2024
• Band/Heft Quelle: 63(2024), 40, Seite 18655-18668
• ISSN Quelle: 1520-510X
• DOI: doi:10.1021/acs.inorgchem.4c02409
• Datenträger: Online-Ressource
• Sprache: eng
• K10plus-PPN: 1919821295

Abstract

The search for an iron analog of the established ruthenium-based catalysts containing methylene-extended 4,5-bis(diorganophosphinomethyl)acridine ligands, [FeHCl(CO)(LR)], resulted in the discovery of a bidentate coordination mode of these usually tridentate pincer ligands toward iron. The acridines nitrogen atom does not coordinate to iron, leading to the formation of iron diphos-type complexes with unusually large cis bite angles of up to 124° as well as trans bite angles around 155°. The iron-containing complexes [FeCl2(κ2-LR)] (R = iPr, Ph), [FeX2(κ2-LCy)] (X = Cl, Br) and [Fe(CO)3(κ2-LR)] (R = iPr, Cy) have been isolated in crystalline form and characterized by spectroscopic methods and mass spectrometry. Their structures were verified unambiguously through X-ray diffraction. The stability of the iron(II) complexes decreased in the order Cy > Ph > iPr and Cl > Br > I, although all iron(II) complexes were found to be relatively stable enough for short-term handling in air in the solid state. Notably, no iron(0) complex of the phenyl derivative could be isolated. The iron(0) complex [Fe(CO)3(κ2-LCy)] was found to be significantly more stable toward hydrolysis and oxygen compared to [Fe(CO)3(κ2-LiPr)] and can be stored in air for months without significant decomposition in the solid state, while [Fe(CO)3(κ2-LiPr)] decomposes in air within seconds. The decomposition products [FeI2(κ2-O2LCy)], [{Fe(CO)3(κ2-HLR)}2] (R = iPr, Cy) and [FeCl2(CO)2(κ1-LCy)(κ1-OLCy)] were identified and characterized crystallographically. The iron(0) complex [Fe(CO)3(κ2-LCy)] is oxidized by [Fe(Cp)2](BPh4) to give the paramagnetic, low-spin iron(I) cation [Fe(CO)3(κ2-LCy)]+. The electron paramagnetic resonance spectrum of the highly sensitive cation as well as density functional theory calculations suggest a partial delocalization of the unpaired electron over the three carbonyl ligands and the acridines aromatic ring system. The catalytic activity and photophysical properties of the complexes have been preliminarily investigated.