Bis(tetrathiafulvalenes) with aromatic bridges: electron delocalization in the oxidized species through EPR and theoretical studies

Abstract

A series of bis(TTF) donors containing aromatic linkers between the two TTF units has been synthesized in order to investigate on the electronic structure of the oxidized species from an experimental and theoretical point of view. A mono(TTF)-pyridine compound has been also prepared and characterized by single-crystal X-ray diffraction analysis. Oxidation of a solution of 2,6-bis(TTF)-pyridine (TTF-Pyr-TTF) or of 1,3-bis(TTF)-benzene (TTF-Bz-TTF) in CH(2)Cl(2) with less than 0.1 equivalent of [Cp(2)Fe][PF(6)] gives rise to a seven-line EPR spectrum consistent with the hyperfine structure calculated by DFT for the corresponding radical monocation. Increasing the proportion of oxidant leads to a four-line hyperfine structure, similar to the quartet pattern observed after oxidation of mono(TTF)-pyridine (Pyr-TTF) or mono(TTF)-benzene (Bz-TTF). In good accordance with the very weak value of J calculated by DFT for the dicationic biradicals these four-line spectra are attributed to [2,6-bis(TTF)-pyridine](2+) and [1,3-bis(TTF)-benzene](2+). Similar experimental results are obtained for 1,4-bis(TTF)-benzene. In this case, however, electrochemical oxidation leads to the monoradical at low potential and to the diradical at higher potential, while only the diradical could be observed by electrochemical oxidation of 2,6-bis(TTF)-pyridine or of 1,3-bis(TTF)-benzene.

TetrathiafulvaleneBenzothiadiazoles as Redox‐Tunable Donor–Acceptor Systems: Synthesis and Photophysical Study

“…Synthesis and characterization : TTFBTD 2 was synthesized by a palladium‐catalyzed Stille‐type coupling reaction between dibromobenzothiadiazole derivative 1 and TTFSnMe 3 (Scheme ), according to a procedure that has been successfully employed in the synthesis of other TTF derivatives 20. With key precursor 4 21 in hand, the synthesis of TTFBTD systems 3 a and 3 b was accomplished through triethylphosphite‐mediated coupling reactions with their corresponding 1,3‐dithiole‐2‐thione derivatives.…”

Tetrathiafulvalene-1,3,5-triazines as (Multi)Donor–Acceptor Systems with Tunable Charge Transfer: Structural, Photophysical, and Theoretical Investigations

“…We have therefore decided to develop a more efficient strategy for the synthesis of TTF-TZ compounds. When the precursors (OMe) 2 -TZ-Cl and (OMe)-TZ-Cl 2 were reacted with the tin derivative TTF-SnMe 3 15 under palladium-catalyzed Stille crosscoupling conditions, the D−A compounds 1 and 2 were isolated in 78% and 75% yields, respectively, after chromatographic workup (Scheme 1). Thus, the cross-coupling strategy is much more adapted than the nucleophilic substitution for the attachment of TTF units to the triazine ring, and it was therefore applied for the preparation of the new compounds 3 and 4.…”

“…4-(Trimethylstannyl)-tetrathiafulvalene and 4-(trimethylstannyl)-4′,5′-bis(methylthio)-tetrathiafulvalene were synthesized according to a procedure previously described …”

Bimetallic neutral palladium (II) bis(dithiolene) complex: Unusual synthesis, structural and theoretical study

“…We noticed initially the formation of the title compound [(Ph 3 P)Pd(edt)] 2 (1), identified after single crystal X-ray analysis (vide infra), as traces of by-product during our attempts of Stille type coupling between TTF-SnMe 3 and various halogenated aromatic substrates in the presence of the standard Pd(0) catalyst Pd(PPh 3 ) 4 [13].…”