Dependence of intervalence-transfer bands for mixed-valence oligo(1,1′-dihexylferrocenylene)s on the oxidation number and the number of ferrocene units from two to six

Abstract

Intervalence-transfer (IT) bands at all of the mixed-valence states of oligo(1,1Ј-dihexylferrocenylene)s from the dimer to the hexamer, 2-6, were determined by analysis of the absorption spectra of the oligomers oxidized quantitatively with 1,1Ј-dichloroferrocenium hexafluorophosphate, 1, in CH 2 Cl 2 -acetone. Characteristic features of the IT bands are a higher energy shift in ν max as the oxidation number for each oligomer increases and a lower energy shift in ν max for the monocationic forms of the oligomers as the number of ferrocene units increases. A simple analysis of the shift in ν max of IT bands was made based on a model assuming that the mixed-valence states are a linear combination of reduced (Red) and oxidized (Ox) nuclei. It is qualitatively rationalized by taking into account the change in neighboring-site combination, especially between Red-Ox and Ox-Ox, formed by photoelectron transfer, which requires extra energy due to the strain in internuclear distance.

Synthesis of the Prototypical Cyclic Metallocene Triad: Mixed‐Valence Properties of [(FeCp)3(trindenyl)] Isomers

“…(2)]16a where E 0 represents the redox asymmetry. It has been reported that Equation (2) is applicable to oligoferrocenes 19. Moreover, oxidation of the structurally correlated bimetallic isomers anti ‐[(FeCp) 2 (indacenediide)] and syn ‐[(FeCp) 2 (indacenediide)] occurs at almost identical potential 3b.…”

Comparative Study of Photochromic Ferrocene‐Conjugated Dimethyldihydropyrene Derivatives

“…Tetra‐ n ‐butylammonium perchlorate (Bu 4 NClO 4 , TCI) was used after recrystallization several times from ethanol (Kanto Chemicals, HPLC grade) and dried under vacuum for 24 h. Ferrocene (Fc; Kanto Chemicals) was recrystallized from hexane, and decamethylferrocene (Fc*; Aldrich) was recrystallized from hexane/MeCN. [Fc(η 5 ‐C 5 H 4 Cl) 2 ]PF 6 was synthesized as reported 18…”

“…[Fc(h 5 -C 5 H 4 Cl) 2 ]PF 6 was synthesized as reported. [18] Bis(ferrocenylethynyl)benzodimethyldihydropyrene ( 1): A solution of tributylstannylethynylferrocene (0.900 g, 1.80 mmol) in dry dimethylform-A C H T U N G T R E N N U N G amide (DMF) (10 mL) was added to a stirred solution of 7 (0.350 g, 0.634 mmol) and PdA C H T U N G T R E N N U N G (PPh 3 ) 4 (85 mg, 0.074 mmol) in dry DMF (20 mL). The red-purple mixture was heated to 368 K, whereupon it turned into a red solution.…”

Syntheses, crystal structures and electrochemical studies of bi- and trimetallic conjugated ferrocene-based complexes

“…1,2 When two or more ferrocenyl fragments are connected to obtain compounds with linked ferrocenes, further interests are envisaged, since intermetallic electronic communication affords a wide range of new applications, and many studies have been made regarding intramolecular electron-exchange reactions. [3][4][5][6][7][8][9] In the search of new materials with electronic communication between terminal subunits, we have focused our interest in the preparation of new conjugated ferrocenyl complexes with end capped nitro, 10 pyridine 11 and nitrile 12 groups. End-capping ferrocene with pyridine and nitrile allows the ferrocenyl subunit to link to different metallic fragments, affording interesting bimetallic complexes, in which the terminal metallic fragments are connected by a conjugated bridge.…”