Use of the TCNQF42− Dianion in the Spontaneous Redox Formation of [FeIII(L−)2][TCNQF4⋅−]2. Issue 7 (9th March 2018)

• Record Type: Journal Article
• Authors: Gass, Ian A.; Lu, Jinzhen; Asadi, Mousa; Lupton, David W.; Forsyth, Craig M.; Geoghegan, Blaise L.; Moubaraki, Boujemaa; Cashion, John D.; Martin, Lisandra L.; Bond, Alan M.; Murray, Keith S.
• Is Part Of: ChemPlusChem. Volume 83:Issue 7(2018)
• Page Start: 658
• Page End: 668
• Publication Date: 2018-03-09
• Subjects: charge transfer -- electrochemistry -- iron -- magnetic properties -- radicals; Chemistry -- Periodicals; 540.5
• DOI: 10.1002/cplu.201800010
• Languages: English
• ISSNs: 2192-6506

Abstract

Abstract: The reaction of [Fe II (L . )2 ](BF4 )2 with Li2 TCNQF4 results in the formation of [Fe III (L − )2 ][TCNQF4 . − ] (1 ) where L . is the radical ligand, 4, 4‐dimethyl‐2, 2‐di(2‐pyridyl)oxazolidine‐ N ‐oxide and TCNQF4 is 2, 3, 5, 6‐tetrafluoro‐7, 7, 8, 8‐tetracyanoquinodimethane. This has been characterised by X‐ray diffraction, Raman and Fourier transform infrared (FTIR) spectroscopy, variable‐temperature magnetic susceptibility, Mössbauer spectroscopy and electrochemistry. X‐ray diffraction studies, magnetic susceptibility measurements and Raman and FTIR spectroscopy suggest the presence of low‐spin Fe III ions, the anionic form (L − ) of the ligand and the anionic radical form of TCNQF4 ; viz. TCNQF4 . − . Li2 TCNQF4 reduces the [Fe II (L . )2 ] 2+ dication, which undergoes a reductively induced oxidation to form the [Fe III (L − )2 ] + monocation resulting in the formation of [Fe III (L − )2 ][TCNQF4 . − ] (1 ), the electrochemistry of which revealed four well‐separated, diffusion‐controlled, one‐electron, reversible processes. Mössbauer spectroscopy and electrochemical measurements suggest the presence of a minor second species, likely to be [Fe II (L . )2 ][TCNQF4 2− ]. Abstract : Radical redox : Li2 TCNQF4 (TCNQ=7, 7, 8, 8‐tetracyanoquinodimethane) reduces the [Fe II (L . )2 ] 2+ dication found in [Fe II (L . )2 ](BF4 )2, which then undergoes a reductively induced oxidation to form the [Fe III (L − )2 ] + monocation resulting in the spontaneous redox formation of [Fe III (L − )2 ][TCNQF4 . − ] (L . /L − are the neutral radical and hydroxylamino anionic form of the neutral radical chelating ligand, 4, 4‐dimethyl‐2, 2‐di(2‐pyridyl)oxazolidine‐ N ‐oxide).