Redox properties of 2,3,7,8-tetramethoxyselenanthrene: a charge-transfer donor

Abstract

The redox properties of 2,3,7,8-tetramethoxyselenanthrene and 2,3,7,8-tetramethoxythianthrene have been studied in solution in order to compare their potential applicability as charge-transfer donors. The selenium compound is the weaker reductant, yielding a stable radical cation and a reactive dication, the former dimerizing in solution. Electron spin resonance and visible absorption spectra of the stable species were obtained. The 1:1 charge-transfer complexes of the above donors with tetracyanoquinodimethane are found to be insulators.

The chemistry of anions derived from tetracyanodiphenoquinodimethane (TCNDQ)

“…Figure 5 shows, indeed, that electrosynthesized solutions of TCNDQ' in DMF-TEAP also do not obey Beer's law, the apparent molar absorptivity at 540 nm again decreasing with increasing concentration of TCNDQ'. A similar phenomenon has been observed in the electronic spectrum of T C N Q~ in solution (17b), and we have previously observed strong self-association of organic radical ions in solution spectroelectrochemical studies (18). Furthermore, this postulate is consistent with our observations that (i) the peak voltammetric current function, i ,~-' v -~~~, for the second anodic maximum increases with decreasing scan rate, v, and (ii) the first oxidation step for TCNDQ2-has a peak current ratio ip,,/ip,a greater than unity (19).…”

“…The solution esr spectrum of other acceptor radical anions (20) and donor radical cations (18,21) have been extremely useful in characterizing these species and studying aggregation (17b) and exchange (22) processes in solution. The esr spectrum of TCNDQ' in D M F is shown in Fig.…”

Dipicolylamine Complexes of Copper(II): Two Different Coordination Geometries in the Same Unit Cell of Cu(Dipica)2(BF4)2

“…Potentials in nonaqueous solution were measured with respect to the Ag + (0.01 M), NEt 4 ClO 4 (0.1 M)/Ag electrode, and may be estimated with reference to the standard hydrogen electrode by the addition of ca . +545 mV …”

Dimerization of thianthrene radical cations as studied by in situ ESR and UV-Vis-NIR voltammetry at different temperatures

“…2 The thianthrene radical cation can also be formed electrochemically, as thianthrene undergoes two distinct reversible one-electron transfer processes under water-and oxygen-free conditions. [3][4][5][6] Kinetic studies by fast scan cyclic voltammetry point to a reversible dimerization of thianthrene and 2,3,7,8-tetramethoxythianthrene radical cations. 7 From semiempirical PM3 calculations the formation of sigma-bonded dimers was suggested.…”