Thianthrene Analogues

Compounds 33 and 34 are analogues of TH in the sense that the central 1,4-di-thiin ring is annulated to two aromatic moieties. 

The central 1,4-dithiin ring in 33 adopts a boat conformation, as is the case for TH, with a 48° fold along the S-S vector in the solid state as shown by X-ray crystallographic analysis [92]. Both 33 and 34 undergo reversible one-electron oxidation to the corresponding radical cation with E1/2=0.93 and 0.77 V, respectively, vs Ag/AgCl as shown by cyclic voltammetry in acetonitrile [92]. There is also an irreversible second oxidation for both compounds at E1/2 ca. 1.5 V. 

The radical cations of benzo-1,4-dithiin 36,1,4-dithiin 37a and some of their derivatives have been prepared and characterized by their EPR spectra [7, 93-96]. 

Compound 37a and its derivatives adopt a boat conformation in the solid state as revealed by X-ray crystallographic structure studies [98-100]. However, the 1,4-dithiin ring in 38 is planar in its complex with acridine [101]. This facilitates 7T-7T stacking of 38 and acridine although their interaction is weak. Furthermore, calculations suggest that there is little energy difference between planar and boat conformers [102]. Thus conformational analysis of 1,4-dithiin is similar to that of thianthrene. 

Electrochemical oxidation of 36, 37a, and their substituted derivatives has been measured. The reported E1/2 vs SCE for the first reversible oxidations to the corresponding radical cations in acetonitrile for 37a, 36, and TH are +0.69, +0.80, and +0.96 V, respectively [103]. All three also show a second irreversible oxidation under these conditions at +1.16, +1.34, and +1.31, respectively. Electrochemical oxidation of 39 has been reported [104]. 

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Treatment of [RuCl(terpy)(bipy)]+ with CF3S03H under N2 gives [Ru(03SCF3)(terpy)(bipy)]+, which when treated with dry air at 110°C for 5h yields the Ru 1 analogue [Ru(03S-CF3)(terpy)(bipy)]2+.1256 Aquation of [Ru(03SCF3)(terpy)(bipy)]2+ occurs readily to give [Ru(terpy)(bipy)OH2]3+.1203,1204,1256 The luminescence and redox chemistry of [Ru(terpy)(bipy)L]2+ (L = OH2, phenothiazine, TV-methylphenothiazine, thianthrene) have been reported.1259... 

TriCTAs and TeCTAs were prepared by stepwise addition of sulfuryl chloride over 4 h at 60°C. The degree of chlorination was found to be three to four (only tri- and tetrachlorinated thianthrenes were observed as reaction products) when all of the parent compound was consumed. One TriCTA and one TeCTA were obtained as main products. In addition, two other TriCTAs, four TeCTAs, and some PeCTAs were observed in minor concentrations. Because of the ortho- and para-directing properties of sulfur in electrophilic aromatic substitution reactions, 237-TriCTA and 2378-TeCTA, the thio analogue of 2378-TeCDD, were obtained as the main products. Mass spectrometry and H NMR were used in the structure verification. 

Dithiin (108), an isomer of (107), has been studied theoretically mainly in the form of its dibenzo-derivatives or their hetero-analogues (109a— c). o Phenoxathiin (109a), thianthrene (109b), and phenothiazine (109c)... 

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