Ferrocenyl-phosphonium ionic liquids – synthesis, characterisation and electrochemistry

Abstract

New unsymmetrically substituted ferrocenyl-phosphonium ionic liquids (ILs) [FcPR2R']NTf2 are synthesized by two or three step syntheses starting from ferrocene, Fc = (C5H5)Fe(C5H4); R = Me, (n)Bu, (n)Hex, Ph; R' = Me, (n)Pr, (n)Bu, Ph; NTf2 = N(SO2CF3)2. The selective synthesis of alkyl phosphines FcPR2via a Friedel-Crafts phosphorylation is highlighted as an alternative for the standard protocol commonly used for ferrocenyl arylphosphines involving lithiation of FcH followed by phosphorylation. The influence of the P-substituents on thermal stability, electrochemical potential, chemical shift, and UV-Vis absorption behavior of the ILs is studied. The phosphonium group acts both as an ionic tag and as an electron-withdrawing substituent directly bound at the Cp-ring position. Therefore the title compounds are attractive for further studies to use them as tunable redox mediators for (photo)electrochemical devices such as dye sensitized solar cells (DSSCs) or redox flow batteries.

Electron‐Transfer Studies of trans‐Platinum Bis(acetylide) Complexes

“…The spectroscopic data correspond with those previously reported. [44] PFc 2 nBu (3c): For the synthesis of 3c, a different synthetic procedure to that previously reported [45] was used. Compound 1 (12.09 g, 0.07 mol) and AlCl 3 (8.67 g, 0.07 mol) were dissolved in n-heptane (200 mL).…”

“…[44] To ferrocene (1, 1.34 g, 7.17 mmol) and potassium-tert-butoxide (0.10 g, 0.90 mmol) in dry tetrahydrofuran (40 mL), tert-butyllithium (5.30 mL, 8.60 mmol) was added dropwise at -75°C. The reaction mixture was stirred for 20 min at -75°C and then warmed to -40°C.…”

Synthesis and characterization of an electroactive ionic liquid based on the ferrocenylsulfonyl(trifluoromethylsulfonyl)imide anion

“…However, there are very few reports on electroactive ILs and there is a very narrow array of available structures and given that the design of a new RIL is hindered by a lack of knowledge of their structure-properties relationships [18][19][20][21][22][23][24]. In addition, the current library of RILs almost exclusively contains structures based on the modification of alkylimidazoliums, with some exceptions from reports on ferrocene-functionalized phosphonium IL [14,25] and metallocenium ILs [26,27]. Our group reported on the development of RIL as redox additive in electrolytes for lithium-ion batteries to protect the cathode against overcharging [28,29].…”

Phosphonium salts and P-ylides

“…5). 134 Functionalisation of the cyclopentadienyl ring was accomplished through a Friedel-Crafts phosphorylation. Wu and co-workers developed the synthesis of ammonium and phosphonium polyoxometallate ionic liquids.…”