Version 1
: Received: 8 January 2024 / Approved: 12 January 2024 / Online: 12 January 2024 (10:42:27 CET)
Version 2
: Received: 26 January 2024 / Approved: 29 January 2024 / Online: 29 January 2024 (04:43:43 CET)
Pokharel, U.R.; Daigle, D.P.; Naquin, S.D.; Engeron, G.S.; Lo, M.A.; Fronczek, F.R. Synthesis, Crystal Structure, and Electrochemistry of Mono- and Bis-Homoannular Ferrocene Derivatives. Crystals2024, 14, 141.
Pokharel, U.R.; Daigle, D.P.; Naquin, S.D.; Engeron, G.S.; Lo, M.A.; Fronczek, F.R. Synthesis, Crystal Structure, and Electrochemistry of Mono- and Bis-Homoannular Ferrocene Derivatives. Crystals 2024, 14, 141.
Pokharel, U.R.; Daigle, D.P.; Naquin, S.D.; Engeron, G.S.; Lo, M.A.; Fronczek, F.R. Synthesis, Crystal Structure, and Electrochemistry of Mono- and Bis-Homoannular Ferrocene Derivatives. Crystals2024, 14, 141.
Pokharel, U.R.; Daigle, D.P.; Naquin, S.D.; Engeron, G.S.; Lo, M.A.; Fronczek, F.R. Synthesis, Crystal Structure, and Electrochemistry of Mono- and Bis-Homoannular Ferrocene Derivatives. Crystals 2024, 14, 141.
Abstract
Two ferrocene derivatives, namely, 1,2-(tetramethylene)-ferrocene and 1,2,1’,2’-bis(tetramethylene)-ferrocene, were synthesized in a four-step reaction sequence starting from ferrocene. Friedel-Craft acylation of ferrocene with succinic anhydride gave mono- or bis(3-carboxypropinoyl)ferrocene depending on the stoichiometry of succinic anhydride. The reduction of the keto groups to methylene, followed by ring-closing using trifluoroacetic anhydride gave 1,2-(α-ketotetramethylene)-ferrocene or 1,2,1’,2’-bis(α-ketotetramethylene)ferrocene. The diastereomeric mixture of the later diketones was separated by column chromatography, characterized by single-crystal X-ray analysis, and assigned their stereochemistry. Reduction of the keto groups to methylene under Clemmensen conditions gave homoannular mono- or bis(tetramethylene) ferrocene derivatives. The molecular structure of 1,2-(tetramethylene)-ferrocene reveals that ipso carbons of the cyclopentadienyl group are 0.023(3) Å farther away from Fe(II) in comparison to its remaining three carbons. Both complexes exhibit lower half-wave oxidation potentials than ferrocene possibly due to the electron-releasing effects of the tetramethylene bridges.
Chemistry and Materials Science, Organic Chemistry
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