New π‐Extended 1,1′‐Disubstituted Ferrocenes with Thioate and Dithioate End Groups

Abstract

Extended π systems based on 1,1′‐aryl or (2‐arylethynyl) disubstitution at ferrocene with thioate or dithioate end groups are reported. In the context of molecular electronics, such end groups are possible alternative end groups for the attachment of molecular wires at gold surfaces. The respective thioates were successfully prepared in high yields via the respective carboxylic acid derivatives. Subsequent treatment with Lawesson's reagent led to the respective dithioates. However, this did not work in the presence of triple bonds, in these cases, product mixtures were formed. On the basis of literature evidence with Woollin's reagent, the selenium analog of Lawesson's reagent, one product was tentatively characterized as a double cyclization product of two triple bonds and two molecules of Lawesson's reagent. Preliminary experiments towards the formation of gold complexes by reaction with a Johnphos gold(I) salt are included.

A Systematic Study of Methyl Carbodithioate Esters as Effective Gold Contact Groups for Single‐Molecule Electronics

“…Analogous ethyl carbodithioate ester complexes have been prepared previously by Butenschön and co-workers for other applications and show the ester remains intact while coordinated to the electron deficient Au I metal centre. [49] The complexation study was carried out with an Au(I) gold atom to represent an electron deficient gold atom, i.e. an atom where electron donation from a ligand is highly favorable.…”

Comparison of Diastereoselective ortho-Metalations and C–H ­Activations of Chiral Ferrocenes

“…Similar attempts by Schmiel and Butenschön in 2017 on diastereoselective Co-catalyzed C–H activation of ( S )- 33 led only to a poor 8% yield of the desired product ( S , S p )- 37 with a low diastereomeric ratio of 5.7:1. 81 The authors decided to use another chiral oxazoline moiety of ferrocene derivative ( S )- 38 as a directing group in the Fe-catalyzed diastereoselective C–H activation. 82 The starting ferrocene derivative was prepared in five reaction steps from ferrocenecarboxylic acid and it afforded the desired product ( S , S p )- 39 as a single diastereomer, albeit in low 17% yield.…”

Comparative enantioseparation of planar chiral ferrocenes on polysaccharide‐based chiral stationary phases

“…[12][13][14] Moreover, the ferrocenium/ ferrocene system (Fc + /Fc) is a versatile redox couple which have proven to be suitable for the preparation of switchable functional systems. 1,15,16 Due to their versatility to access molecular wires and responsive switchable systems and materials, [17][18][19] particular attention has been devoted to the so-called "π-extended ferrocenyl frameworks," which are featured by delocalized orbital networks based on the combination of a ferrocene unit and a π-conjugated extended cloud, such as the ethynyl group. 13,20 Planar chiral aryl ethynyl ferrocenes have been used as intermediates for the preparation of helical ferrocenes showing peculiar chiroptical properties with very high optical value and huge intensity of the circular dichroism signals.…”