Benzo-Bridged Bis(1,2,3-dithiazoles) and Their Selenium Analogues. Preparation, Molecular and Electronic Structures, and Redox Chemistry

Abstract

The condensation of diaminobenzenedithiol with sulfur monochloride leads to the chloride salt of the radical cation of 3,6-dichlorobenzo[1,2-d:4,5-d‘]bis(1,2,3-dithiazole), dichloro-[BB-123-DTA][Cl], which can be reduced to neutral dichloro-[BB-123-DTA] with triphenylantimony. A similar condensation with selenium tetrachloride leads, upon reduction, to the corresponding bis(1,2,3-thiaselenazole) dichloro-[BB-123-TSA]. The crystal and molecular structures of both compounds have been determined by X-ray diffraction. Both compounds, which are formally antiaromatic 16π-systems, exhibit internal bond lengths consistent with a quinoid formulation. The radical cations of both rings have been characterized by ESR spectroscopy; for dichloro-[BB-123-DTA]+ g = 2.0114 and a N = 0.201 mT, while for dichloro-[BB-123-TSA]+ g = 2.021 and a N = 0.44 mT. Further oxidation of both rings affords the corresponding dications, both of which have been characterized crystallographically as their AlCl4 - salts. The structural features of these compounds are consistent with those expected for dithiazolylium (or thiaselenazolylium) derivatives. The structure and redox chemistry of the benzo[1,2-d:4,5-d‘]bis(1,2,3-dithiazole) framework is discussed in the light of the results of ab initio calculations.

Radical Cation and Dication Derived from 4,8‐Diethylbenzo[1,2‐d:4,5‐d′]bis[1,2,3]trithiole [DEBBT]: Change of Electronic State from Singlet‐State Dication DEBBT(2+)‐S to Triplet‐State Dimer 2DEBBT(2+)‐T in D2SO4 and CD3CN Solutions

“…The ESR signal of the dication resembles that of the radical cation, and hence, in the paired form, the two radical centers on the trithiole rings are expected to be effectively independent of each other. [4,5] To estimate the quantity of the dication, DEBBT 1-O and sodium 2,2-dimethyl-2-silapentane-5-sulfonate (DSS) (an internal standard) were dissolved in concentrated D 2 SO 4 (DEBBT 1-O/DSS ϭ 1:1), after which the 1 H NMR spectrum of the solution was measured (Figure 2). The integral ratio of DEBBT(2؉)-S (2 ϫ CH 2 ) and DSS (CH 2 SO 3 Na) was determined from the spectrum as DEBBT(2؉)-S/DSS ϭ 2.643:1.325.…”

Preparation and Characterization of a Neutral π-Radical Molecular Conductor

“…21 Reduction of the dithiazolylium cation so formed then affords the neutral radical 3. 22 Although a range of radicals has been well-characterized spectroscopically, nothing is known of the molecular or solidstate structures of these systems. In this work we constructed the target molecule starting from the known compound 5,6-dichloro-1,2,5-thiadiazolo[3,4-b]pyrazine (6).…”

Generation and detection of the radical cation and the dication derived from 4,9‐diethyl[1,4]dihydrodithiino[5,6‐f]benzotrithiole and its 5‐oxide

“…In contrast, the unsymmetrically substituted dication, MBT(2+), generated from 5-methylsulfinyl-6-methylthio-4,7-diethylbenzo [1,2,3]trithiole (MBT oxide) on treatment with D 2 SO 4 , was active for ESR, while silent for NMR [14]. To examine the stability and the electronic state of unsymmetrically substituted cyclic dications, 4,9-diethyl [1,4]dihydrodithiino [5,6-f ]benzotrithiole (DTBT) was oxidized by single-electron oxidizing reagents, and 4,9-diethyl [1,4]dihydrodithiino [5,6f ]benzotrithiole 5-oxide (DTBT 5-O) was treated with concentrated D 2 SO 4 [15]. This paper reports the generation of the dication, DTBT(2+), and its characterization with 1 H NMR, 13 C NMR, ESR, and the DFT (density functional theory) calculations.…”