Dithiazoles

4-Dithiazoles. - The luminescence spectra of (298) have been discussed in terms of intramolecular charge-transfer from the thione group to the ring. Vibrational frequencies were obtained from the luminescence spectra the structures and energies of mass-spectral fragments that were derived from 

The reaction of Pt(PPh3)4 with (302) is solvent-dependent in CHCI3, [303 M = Pt(PPh3)2] is formed, whereas in CgHg the product is [303 M = PtCl-(PPha)].  

3-Dithiazoles.—1,2,3-Benzodithiazolium chloride (247 X = Y = S), obtained from the reaction between aromatic amines and disulphur dichloride (c/. Vol. 1, p. 163), is hydrolysed in aqueous sodium hydroxide to the 2-amino-thiophenol, via the 1,2,3-benzothiazolium hydroxide.It is also possible to isolate the 2-oxide (248 X = Y = S, Z — O), using aqueous sodium carbonate the selenathiadiazolium salt (247 X = Se, Y = S) yields an analogous product (248 X - Se, Y = S, Z — O), whilst the isomer (247 X = S, Y = Se) is converted into the diselenide (249). 2-Aminonaphthalene-l-sulphonic acid S. Mataka, K. Takahashi, and M. Tashiro, Synthesis, 1979, 687. 

Tashiro and S. Mataka, Jpn. Kokai Tokkyo Koho 79 132 572 Chem. Abstr., 1980,92, 111 022). S. Mataka, K. Takahashi, and M. Tashiro, Chem. Lett., 1979, 1033. 

5-thiones 273 as final products, methyl isothiocyanate being the extruded species (91JOC3268). 

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Dithiazole-3-thiones alkylation, 6, 923 nucleophilic attack, 6, 915 photoreactions... 

Dithiazoles are the most common and thoroughly researched of the three azoles presented in this chapter. On the whole, the research on all three heterocyclic types has expanded appreciably since the publication of the first edition of Comprehensive Heterocyclic Chemistry (CHEC-I) about 170 references for the 12 years since 1980 compared to about 110 references for the 20 years prior to 1980. 

MNDO calculation of AH for 3-amino-1,2,4-dithiazole-5-thione indicated that, of its possible isomeric forms (7), (8), and (9) (R = H), (7) is the most favorable. This structure had been found experimentally in the crystal and in solution but the differences are small and structures (8) and (9) may also take part in reactions. In fact, methylation of (7 R = H) gives (9 R = Me) shown by MNDO calculation to possess the lowest AHf <82JCR(S)65>. The MNDO method was used to calculate the structure and energy of 3-amino-1,2,4-dithiazole-5-one, its molecular cation and also its fragmentation ions <82MI 4i3-oi>. 

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