Ferrocenes with a Persulfurated Cyclopentadienyl Ring: Synthesis, Structural Studies, and Optoelectronic Properties

Abstract

Persulfurateda renes are af ascinating class of functional molecules with aw ider ange of potentiala pplications. Ferrocenes are also am ultifaceted class of aromatic compounds that can easily be finetuned for an enormous variety of desired properties. Ac ombinationo f both substancec lasses might yield an even wider field of applications. Herein, we describe the synthesis of two ferrocenesw ith one persulfurated cyclopentadienyl ring [C 5 (SR) 5 ], with R = Me or Ph, together with their crystal structures, optical, and electrochemical properties. Both crystal structures show significant intramolecular sulfuriron interactions as well as weak intermoleculars ulfurcontacts. Cyclovoltammetry of the [C 5 (SPh) 5 ]c ompound shows ah igho xidationp otentialo f6 51 mV vs. FcH/FcH + .Persulfurated arenes still remain an underexploited field of chemistry,d espite their highly interesting physical organic properties and their numerous possible applications, ranging from ion-selectivem embranes over organic conductors and ferromagnets to cation sensors andl iquid crystals. [1] This statement made by M. Gingras in af ascinatingr eview article in this journal more than 10 years ago is still valid. There have been, however,s everali nteresting additions to this field, particularly with extended aromatic systems. Per(arylthio)corannulenes and -coronenes have found potential applicationa sp hotovoltaic devices [2] and for molecular electronics. [3] Substituted hexakis(phenylthio)benzenes showeds trong phosphorescence in the solid state with the potential of OLED applications. [4] Dendrimersw ith a[ C 6 (SAr) 6 ]c ore, so-called" molecular asterisks" have been used as multifunctional ligandsf or the preparation of luminescents ensors and asymmetric metal catalysis. [5] The interesting electronic properties sharedb yt his compound class are mainly due to the fact that "phenylthio substituents attached to aromatic cores result in ar eduction of the HOMO-LUMOg ap", [1, 2a] "primarily due to LUMO stabilization". [6] Upon addition of SPh groups ab athochromic shift of the longest wavelength absorption by 10-15 nm is observed together with an increaseofthereductionpotential by 0.1 V. [2b] Metallocenes are another very important group of aromatics with very interestinge lectronic properties. However,w hile quite af ew metal-freep ersulfurated arenes have been studied, there seem to be no reports of persulfuratedferrocenes. The fivefolds ymmetry of metallocenes would create as tructural motifr arely found with thioether-based "moleculara sterisks" (Scheme 1). [7] While the syntheses of persulfurated cyclopentadienyl anions[ C 5 (SR) 5 ] À (R = Me, Ph) was already reported in the 1980s, [8] attempts to prepare metallocenes from them via reactions with metal halidesm et with failure. However,t he complexes[ C 5 (SMe) 5 ]ML n (ML n = Mn(CO) 3 ,R uCp*) could be obtainedv ia post-functionalization of an already coordinated cyclopentadienyl ring. [9,10] Transfer of this syntheticp rotocol using perhalogenatedo rp ermercurated ferroce...

Evidence for “Halogen‐Dance” and Ring‐Exchange Reactions in Chloro‐methylthio‐ferrocenes

“…In 2019, we reported the synthesis of [C 5 (SMe) 5 ]Fe[C 5 H 5 ], starting from bromoferrocene. [13] Here we report some unexpected results we obtained when trying to prepare decakis(methylthio)ferrocene, which show strong evidence for the occurrence of halogen dance, and in part of ring exchange reactions.…”

“…First we considered the following approach towards the synthesis of [C 5 (SMe One approach was based on our synthesis of [C 5 (SMe) 5 ]Fe-[C 5 H 5 ] [13] using [C 5 Cl 5 ]Fe[C 5 H 4 Br] (2a, Scheme 1) as starting material. For this purpose, 1a was deprotonated with LiTMP, followed by addition of tetrabromoethane.…”

“…90 % purity; corresponding to ca. 0.34 mmol, 31 % based on 2a)1 H NMR (270 MHz, CDCl 3 ): δ= 4.43 ("dd", J = 2.7/1.5 Hz, 1H), 4.29 ("t", J = 2.8 Hz, 1H), 4.25 ("dd", J = 2.8/1.5 Hz, 1H), 2.33 (s, 3H), 2.27 (s, 3H);13 C NMR (100 MHz, CDCl 3 ): δ = 93.9, 93.5, 93.4, 89.9 (C 5 Cl 4 ), 83.5 (CBr), 79.8, 77.1, 75.3 (C 5 H 3 ), 76.6 (CS), 18.7, 16.6 (SCH 3 ). MS (DEI): m/z = 494.2 (M + , 100 %), 353.2 (C 11 H 6 Cl 2 BrS 2 , 35 %), 188.9/190.9 (C 5 H 6 BrS, 80 %).…”

Exploring the boundaries of ferrocenesulfonyl fluoride chemistry

“…This might be at the origin of the peculiar orientation of the phenylthio substituent on the compound 15. Indeed, while the phenyl ring of this substituent is usually observed pointing up in the ferrocene series, 56,84,[160][161][162][163] it is here tilted, probably due to this oxygen-sulfur interaction. Various halogen bonds (XB) were also identified at the solid state, 164 mainly for iodinated ferrocenesulfonyl fluorides.…”

From ferrocene to decasubstituted enantiopure ferrocene-1,1′-disulfoxide derivatives

“…However, while the trimethylsilyl group had almost no effect (compound R p , R p -2f ), the introduction of two phenylthio substituents lowered the E 1/2 value by −0.11 V, a surprising result considering the increase of E 1/2 by +0.13 V per phenylthio substituent already observed. 41,51 From the tetrasubstituted ferrocene R p , R p -2d , the introduction of two iodine atoms next to the fluorine raised the redox potential by +0.08 V per iodine. However, when the iodine atoms were introduced remoted from another group (compound R P , R P -6′h-desi ), the redox potential increased by +0.13 V per iodine, in better agreement with the +0.15 V expected value.…”