1.2- Dithiole-3-thiones and 1,2-dithiol-3-ones

Dithiole-3-thiones and l,2-dithiol-3-ones will not be treated in separate sections in this survey, as very few papers dealing with l,2-dithiol-3-ones... 

IR and Raman spectra of a series of l,2-dithiole-3-thiones and 1,2-dithiol-3-ones have been recorded and interpreted.274 Sixteen of the eighteen fundamental ring vibrations of the parent l,2-dithiole-3-thione have been observed, and most of the substituent frequencies have been assigned. 

The heats of formation for three l,2-dithiole-3-thiones and l,2-dithiol-3-ones indicate that the 1,2-dithiole system possesses a delocalized 7r-electron sextet.264... 

From H-NMR spectra of l,2-dithiole-3-thiones and l,2-dithiol-3-ones it was not possible to draw conclusions concerning the pseudoaromatic character of the l,2-dithiole-3-thione system.277 Proton chemical shifts of methyl substituents are in agreement with values reported for methyl substituents in aromatic systems.278 Calculated diamagnetic and paramagnetic anisotropies for a series of l,2-dithiole-3-thiones and l,2-dithiol-3-ones have been compared with observed chemical shifts. Analysis of these data suggests that a phenyl substituent in position 5 is nearly coplanar with the dithiole nucleus and that the 1,2-dithiole nucleus is an electron-attracting group. ... 

Dithiole-3-ones and 1,2-dithiole-3-thiones appear to be nearly planar and Brown el al. 237 examined the PMR spectra of a large number of compounds in this series, but it was not possible to make any firm conclusion concerning the aromaticity of the systems, although it seems likely that the order of the C-4-C-5 bond is less than 2. More recently238 linear correla-... 

The trivial transformation of 1,2-dithiol-3-ones into 1,2-dithiole-3-thiones by means of phosphorus pentasulfide and analogous sulfurating agents will not be treated in this section. 

A linear correlation of H and C shifts of adjacent ring positions and between the ring and some substituents in 1,2-dithiol-3-ones (2a), 1,2-dithiole-3-thiones (2b), and 1,2-dithiolium ions (3), indicated that the changes in the electron distribution in the ring were responsible for the shift effects <87PS(29)187>, and C NMR spectroscopy was used to confirm the structure of the l,2-dithiolo[l,2-ajdiium ion (5) <89G617>. 

With the help of TLC on silica gel G, Mayer et al. [54] have investigated many heterocyclic sulphur compounds of the trithione (I) (1,2-dithiol-3-thiones) and dithione (II) (l,2-dithiol-3-ones) types, their anils (III), the l,2-thiazoline-5-thiones (IV) and xanthane hydride (V). Petrol ether-benzene (50 + 50) or carbon disulphide are good solvents. 

The vibrational spectra of 1,2-dithiole-3-thione 46 and 1,2-dithiol-3-one 47 were computed at the DFT and MP2 levels (Scheme 31) [98VS77]. Most remarkably, the uniformly scaled MP2 fundamentals are in better agreement with experimental data than the corresponding DFT frequencies. 

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