Abstract
Woodward and co-workers in 1952 characterised the unique structural features of ferrocene (the first sandwich compound), demonstrated its aromatic nature and observed that on treatment with mild oxidising agents (aqueous Ag2SO4, p-benzoquinone in organic solvents) the orange solution of ferrocene (Fc) turned blue due to the formation of ferrocenium (Fc+). A few months later, the one-electron Fc/Fc+ redox change was characterised polarographically by Page and Wilkinson with E1/2 = 0.31 V vs SCE (0.56 V vs NHE) in ethanol/water 9:1. Since then ferrocene has become an icon of organometallic electrochemistry. Owing to the stability of its molecular framework, to the ease of functionalisation at the cyclopentadienyl rings and to the fast, reversible and kinetically uncomplicated Fc/Fc+ redox change, ferrocene has been used as a building block for the design of switchable functional systems. In this review, we will consider (1) electrochemical sensors for metal ions, anions and metal–anion pairs operating through the Fc/Fc+ redox change, (2) ferrocene-based redox switches of fluorescence and (3) cross-transport of electrons and anions through a liquid membrane mediated by lipophilic ferrocene derivatives.Graphic abstract
Highlights
The synthesis of ferrocene ([Fe(η5-C5H5)2]) and the elucidation of its structural and bonding properties in the early 1950s changed the way of thinking about coordination chemistry and promoted the tumultuous
Peter Pauson (1925–2013), a British postdoctoral fellow at the Duquesne University in Pittsburgh, aged 26, was interested in verifying the possible aromatic nature of fulvalene (1) and attempted its synthesis according to the two following steps: (1) coupling of two molecules of cyclopentadienylmagnesium bromide to give the dihydro compound 2, (2) dehydrogenation of 2 with F eCl3 to give 1
Ferrocene is currently abbreviated to Fc. [Fe(C5H5)2]+ was named by Woodward ferricinium [5], but it is today universally called ferrocenium
Summary
ChemTexts (2020) 6:22 development of organometallic chemistry (the chemistry of the metal–carbon interaction). The authors suggested a structural arrangement in which iron is in-between two parallel cyclopentadienyl rings, as illustrated by the beautiful drawing in Fig. 2 (formulae a and b) Such a genial intuition was supported by a single experimental observation: the infrared absorption spectrum contained a single sharp band at 3050 cm−1, which indicated the presence in the compound of C–H bonds of only one type. He and his Harvard group rapidly extended the concept of the “sandwich” structure with a stream of seminal papers, laying a large part of the basis of transition metal organometallic chemistry In spite of these brilliant results, Wilkinson failed to get tenure and left Harvard in January and moved to London, where he was
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
