Benzo-2,l,3-thiadiazol

One of the frequently discussed problems is the coordination mode in complexes of benzo-2,l,3-thiadiazole (A = S) and its selenium analogue (A = Se), (174) or (175) (72ZOB592, 72ZOB2049). X-ray studies indicate that only the N-M coordination (174) is realized. The same mode is characteristic for the complexes of 1,2,3-thiadiazole and 1,2,3-selenadiazole (176). However, the X-ray analysis shows that the coordination via the A atom cannot be excluded, e.g., tellurium may serve as the donor site in the... 

Amongst the N,S-azole ligands [8,13], benzo-2,l,3-thiadiazol deserves a special mention. The controversial question about the possibility of one particular kind of coordination within the complexes formed from benzo-2,l,3-thiadiazol, one in which only one atom of the heterocycle, either N or S, was able to participate [8,13], was solved by x-ray structure studies in favor of the N-coordination 489 [882], However, the examples of the kinds of coordination presented by the sulfur atom in the thiophene cycle (Sec. 2.2.4.5) do not exclude the possibility of M — S binding, particularly when using softer (i.e., Pt, Pd) Pearson acids. 

Benzothiadiazoles and 2,1,3-Benzoselenadiazoles. - Biologically active substances among benzo-2,l,3-thiadiazole derivatives have been reviewed, with 83 references. The synthesis of 4-bromobenzo-2,l,3-thiadiazole-7-... 

It should be noted that a number of SPC polymers which contain other heterocycles have been prepared, motivated by their promising optical or electrical properties. Examples include pyridine (65) [123], pyrrole (66) [124], oxadiazole (67) [125], selenophene (68) [126], benzo[2,l,3]thiadiazole (69) [127], benzo[2,l,3]selenadiazole (70) [126], perylene bisimide (71) [128], 1,4-diketo- pyrrolo[3,4-c]pyrrole-l,4-dione (72 and 73) [127,129], and triphenyleamine (74) [127] as part of the polymer backbone by SPC (Figure 19c). Specifically for metal complexation, porphyrin [130], difluoroboraindacene [131], bipyridine [132], phenanthroHne [113], terpyridine [133, 134], and the like [123] were embedded in the backbone. In this context, an interesting report was submitted by Rehahn et al., in which l,l -ferrocenyl units were incorporated into a PPP (Figure 22.20). Due to a low-energy barrier for rotation around the Cp-Fe-Cp axes (Cp = cyclopentadienyl), the obtained polymer 75 was assumed to take randomly coiled conformations [135]. 

Several random poly(arylene-vinylene)s have been obtained from benzo[2,l,3]thiadiazole and 9,9-dialkylfluorene or 1,4-dialkoxybenzene moieties by a Suzuki-Heck reaction [149]. The monomers used are shown in Figure 3.19. 

Huang X, Dong Y, Meng J, Cheng Y, Zhu C. Fluorescence polymer incorporating triazole and benzo[2,l,3]thiadiazole moieties for Ni + detection. Synlett 2010 12 1841. ... 

Morikita, T., I. Yamaguchi, and T. Yamamoto. 2001. New charge transfer-type p-conjugated poly(aryleneethynylene) containing benzo[2,l,3]thiadiazole as the electron-accepting unit. Adv Mater 13 1862. 

Anion radicals of benzo-2,l,3-thia(and selena)diazole have been produced by metal reduction in several solvents at low temperatures, and their electron spin resonance has been studied. The reductive desulphurization of substituted benzo-2,l,3-thiadiazoles by stannous chloride in concentrated hydrochloric acid gives o-phenylenediamines in 80—90% yields. The stability of the heterocyclics against reduction increases with the number of chlorine substituents. ... 

The oxidative degradation of benzo-2,l,3-thiadiazole by chromic acid produces 4,5-dicarboxy-l,2,5-thiadiazole (250) (up to 78%), which is decarboxylated in nitrobenzene at 160 °C to the 4-monocarboxylic acid (251). The acids give the usual salts and derivatives. ... 

The bromination of benzo-2,l,3-thiadiazole (243) in boiling 47% hydro-bromic acid or nitric acid produces successively the 4-bromo- (252) and 4,7-dibromo-derivatives (253), followed by more highly brominated species. The previously reported addition product is not formed under these conditions, which favour electrophilic attack of Br+ at C-4 (or 7) involving a [Pg.754]

Benzo-2,l,3-thiadiazole-5-acetic acid (255) yields, by conventional methods, A -(2-phenylisopropyl)benzo-2,l,3-thiadiazole-5-acetamide (256). Reduction with stannous chloride in concentrated hydrochloric acid opens the hetero-ring, yielding iV-(2-phenylisopropyl)-3,4-diaminophenylacet-amide (257). ... 

Figure 5.10 Schemes of the device architectures of unannealed (a) and annealed (b) nanofiber OLEDs based on the hght-emitting polymer, poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-( 1,4-benzo- 2,l -3 -thiadiazole)] (in this figure, F8BT). Annealing leads to separation of the PEO and the conjugated polymer components, and ultimately to current conduction and electroluminescence from the Hght-emitting nanofibers. Adapted with permission from Ref 136, ACS Nano, 2011, 5, 5572-5578. Doi 10.102 l/nn201029c. Copyright 2011, American Chemical Society.

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