1,3,4-Thiadiazole -2,5-dithiol

Treatment of the dipotassium salt of 1,3,4-thiadiazole-2,5-dithiol with difunctional ligands, e.g., l,6-i>is(diphenylphosphino)hexane, a,a -fois(diphenylphosphino)-p-xylene, and 1,1 -fcis(diphenylphosphino)ferrocene, in a 1 1 ratio gave the desired cyclic (45-65 %), as well as oligomeric, dinuclear materials <01IC6266>. 

Synonyms Bismuthiol I Busmuthiol 2,5-Dimercaptothiadiazole DMTD 1,3,4-Thiadiazole-2,5-dithiol... 

Formation of Metal Complexes. 1,3,4-Thiadiazole-2,5-dithiol, a potential analytical reagent for the detection and determination of cations, forms complex salts with Cu , Zn", Ag, Cd , T1 , Pb , Pd°, and Pt°. The Cu , Ag , and TP complexes are linear those of the other ions are tetrahedral. Bonding occurs through the thione- or thiol-sulphur, except in the Pd° and Pt° complexes, where it involves the nitrogen. The complexes of Ru ", Ru", Rh , Pd, Ir , and Pt were similarly studied. ... 

Phenyl-l,2,3-thiadiazole (513) as well as the 5-phenyl isomer (514) both lose N2 on photolysis. The 1,3-dithiole derivative shown was formed from both thiadiazoles (58LA(614)4). 

Thermolysis of the 1,2,3-thiadiazoles (545) in the presence of carbon disulfide leads to the thiocarbonyl carbene (546) adduct, the ring-fused l,3-dithiole-2-thione (547) (76JOC730). 

A range of 4-substituted l,3-dithiole-2-thiones (71) and 2,6-substituted 1,4-dithiafulvalenes (73) were synthesised from 4-substimted 1,2,3-thiadiazoles (72). Reaction of (72) with NaH in a mixture of CS2 and acetonitrile led to the formation of (71), whereas absence of CS2 gave fulvalenes (73). This route was found to be very efficient for the preparation of 4-formyl-1,3-dithiole-2-thione (71 R = CHO), which was previously difficult to prepare, and thus allowed the synthesis of the novel 2,6(7)-bisformyltetraAiafulvalene (74) <96T3171>. 

The base-catalyzed fragmentation of 4-alkyl-l,2,3-thiadiazoles is a useful method for the preparation of alkyne-1-thiolates <1996T3171>. These alkyne-l-thiolates can then react with carbon disulfide to afford l,3-dithiole-2-thiones. This strategy has been developed to give a synthesis of some novel tetrathiafulvene derivatives <1996T3171>. 

Another example of a polymer formation is the oxidation of l,3,4-thiadiazole-2,5-dithiol [27] including the formation of an intermediate disulfide (5). As the latter is... 

Thieno[2,3-r 1-l,2,3-thiadiazoles 40a-f heated with CS2 in a double compartment autoclave produced thieno[2,3-rfl-l,3-dithiol-2-thiones 41a-f <2001MOL145>. In addition to the thermolysis product 41e, thieno[2,3- / -l,2,3-thia-diazoles 40e also produced bisthieno[2,3-/ 2, 3 -< ][l,4]dithiine 42 in 36% yield (Equation 3). 

The cyclic voltammograms of thiadiazole fused [2,5-(l,3-dithiol-2-ylidene)-l,3,4,6-tetrathiapentalenes], BDT-TTPs 88, in benzonitrile exhibited four pairs of redox waves corresponding to one-electron transfer processes at 4-0.60, 4-0.81, 4-1.30, and 4-1.47 V (vs. saturated calomel electrode (SCE)). The El values are a little higher than that of 4,5-bis(methylthio)-BDT-TTP (4-0.49 V). The difference is attributed to the electron-withdrawing character of the fused thiadiazole ring on the bicycle <1997SM(86)1821>. 

Upon treatment with CS2 at 170°C, 4,6-dihydro thieno[3,4-d]-l,2,3-thiadiazole (70) yielded 4,6-dihydrothieno[3,4-(/]-1,3-dithiole-2-thione (71), which was a useful intermediate for the synthesis of a novel organic conductor <89TL7249>. 

A photochemical path to l,3-dithiole-2-thione has been reported (61E566). Photolysis of 1,2,3-thiadiazole in carbon disulfide produces an intermediate C2H2S fragment which is. trapped by carbon disulfide to give the l,3-dithiole-2-thione (21). A similar, albeit thermal, reaction of the 1,2,3-thiadiazole derivatives (339) in the presence of carbon disulfide yields at 215 °C the l,3-dithiole-2-thione compounds (340) (76JOC730). 

Heterocyclic analogues of benzenedithiolates are also available. 3,4-Thio-phene-dithiolate is generated from the corresponding dibromothiophene (44). The isoelectronic but inorganic l,2,5-thiadiazole-3,4-dithiolate, [SN2C2S2]2 (tdas, see Fig. 2) can be prepared by sulfidation of SN2(CC1)2 the dianion forms bis(chelate) derivatives of Ni(II) and Fe(III) (45). 

Potential 2-hydroxy- and 2-mercapto-l,3,4-thiadiazoles have been examined both by infrared and by ultraviolet spectra in the solid state and in solution by Sheinker et They concluded that these compounds exist in the 2-oxo and 2-thione forms, respectively. To 2,5-dimercapto-l,3,4-thiadiazole the 2-mercapto-5-thione structure (155) was given. The structure of this compound has been the subject of some controversy. Stanovnik and TiSler have added some valuable arguments to the discussion. They measured the pKfl values of 155, its iV-methyl, iV -phenyl, and iV -phenyl-/S-methyl derivatives (156), and of the conjugate acids of these and the S-methyl derivative (pKn ) (Table III). In all compounds 156 with R = H, the infrared spectrum showed an absorption band near 2300 cm characteristic of the SH group. They also had pK i values near —1.5, Avhich in connection with the infrared evidence was taken as characteristic of an SH group in this situation. Since the 2,5-dithiol structure is excluded by ultraviolet spectral evidence, the 2-mercapto-5-thione structure (155) seems rather well established. It has previously been shown bj Thorn to predominate in chloroform solution, whereas he concluded that the dithione form (157) should predominate in ethanol solution. However, the pK i value for 155, — 1.36, makes it rather probable that Thorn used the monoanion of 155 instead of the acid itself for spectral comparison, and in that case his conclusions have a very weak foundation. 

Thiete structures have been suggested as fragmentation products in the mass spectra of a thietane fused to a 3-lactam, an ortho disulfide of a thiolbenzoate ester, -propanethiol, thiirane carboxylic acid esters, isothiazoles, thiazoles, 1,3-dithiole 2-thiones, 1,3-dithiolene-2-ones, S-ethyl thio-benzoate, and thianaphthene sulfones. Tetramethylthiete may have been formed on thermolysis of the p-toluenesulfonyl-hydrazone of 2,2,4,4-tetramethyl-3-thietanone. " Thiete 2-thione may be an intermediate in the decomposition of 1,2-ditholium salts by the action of bases. " 2,2-Diphenyl-2H-thiete is suggested as an intermediate in the reaction of diphenyldiazomethane with 1,2,3-benzo-thiadiazole which yields 9-phenylthioxanthene and three other products. ... 

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