Ferrocenyl–Bipyridinium Cations and Their Platinum Complexes Related to Viologens – Preparation, Redox Properties, and Crystal Structures

Abstract

N‐R1‐N′‐R2‐4,4′‐Bipyridinium and N‐R1‐4,4′‐bipyridinium salts containing ferrocenyl substituents were prepared as donor–acceptor compounds (R1 = ferrocenyl, ferrocenylphenyl; R2 = ferrocenyl, ferrocenylphenyl, phenyl, methyl). Platinum(II)‐bridged diferrocene compounds were prepared by using the N‐R1‐4,4′‐bipyridinium ligands. These compounds display multistage redox properties. The redox potentials of the ferrocenyl and bipyridinium moieties in these compounds are independently affected by molecular modifications, which indicates that conjugation between the donor and acceptor moieties is less effective. Single‐crystal X‐ray diffraction analyses revealed large twist angles between the two moieties in the solid state. The compounds exhibit broad charge‐transfer absorption bands in the range 450–800 nm. No electronic communication was observed between the terminal ferrocenes in the diferrocene complexes.

Supramolecular complexes involving non-symmetric viologen cations and hexacyanoferrate(ii) anions. A spectroscopic, crystallographic and computational study

“…The synthesis of this compound has been reported before. 48,49 0.980 g (1.56 mmol) of the compound 3 were easily dissolved in 6 mL of dry acetonitrile. To this solution, a solution of 4.20 g tetraethylammonium chloride (25.3 mmol) in 12 mL dry acetonitrile, was added.…”

Photoinduced Charge Shifts and Electron Transfer in Viologen–Tetraphenylborate Complexes: Push–Pull Character of the Exciplex

“…Although its most common electron transfer reactions involve the ground state of MV 2+ , its first photoexcited singlet state is also an excellent electron acceptor whose photoacidity in water and reactivity with alcohol solvents have previously been investigated using ultrafast spectroscopy under dilute (nonion paired) conditions. In this paper, we report ultrafast spectroscopic results for viologen ion-pair complexes − with a tetraarylborate anion, where the charge transfer transition leads to significant structural changes in the MV framework.…”