Dithiolium Ion

Cation 73, synthesized a short time ago,90 is the simplest known derivative of the 1,2-dithiolium ion. Figure 7 presents molecular diagrams of 75 and 77. 

Equally interesting is the situation in the second class of compounds studied (analogues of non-alternant hydrocarbons), which is best divided into two sub-groups analogues of the tropylium ion and analogues of azulene. The empirical correlation of experimental and theoretical excitation energies studied requires a further subdivision into compounds with one heteroatom (e.g. thiopyrylium ion) and two heteroatoms, either adjacent (e.g., 1,2-dithiolium ion) or non-adjacent (e.g., 1,3-dithiolium ion). Experimental and theoretical data are presented in Table VII. Table VIII summarizes data for the derivatives of dithiolia. Figure 15 shows the absorption curves of 1-benzo-... 

The 1,2-dithiolium (158) and 1,3-dithiolium ions (159) are iso-Tr-electronic with the tropylium ion, from which they may be formally derived by replacing two pairs of double bonds by sulfur atoms. Structural data and calculations demonstrate that the rings are substantially stabilized by -ir-electron delocalization. 

The MS fragmentation patterns of dithio-/J-diketonato complexes differ from those of both /J-diketonato and monothio-/J-diketonato complexes. The mass spectra of bivalent dithioacetyl-acetonato complexes are characterized by a molecular ion peak M and a much stronger peak for L+ due to the formation of the 3,5-dimethyl-l,2-dithiolium ion another peak at tn/e 96 is due to the loss of HS from the dithiolium cation. The mass spectra of nickel complexes of dithio-/ -diketones are dominated by fragmentation products of the uncomplexed oxidized ligand, which is consistent with the low stability of dithio-/J-diketones and the greater stability of the 1,2-dithiolium... 

Another characteristic of electrophilic reactions of pseudoazulenes is the application of numerous cations as the electrophile, for example, diazonium salts and Vilsmeier- Haack s reagent (see Table VI), tropylium ion,135 triphenylmethyl cation,"4 pyrylium ion,119 and dithiolium ion.166 Very stable cations are formed (e.g., 120) addition of base releases the substituted pseudoazulene (see example in Eq. 10). Generally reactions of this type are thermodynamically favored (see also Section IV,B). The site of substitution... 

A dithiafulvene (1) can form a 1,3-dithiolium cation by an easy one-electron oxidation, as a result of its electron-donating property. The 1,3-dithiolium ion is an unsaturated five-membered-ring cation in which each sulfur atom contributes a pair of 3n electrons and, consequently, would be expected to show aromatic stability [1, 2]. The chemistry of the dithiafulvene and its... 

Phosphorus oxychloride reacts with l,2-dithiol-3-ones, giving 3-chloro-l,2-dithiolium ions. If this reaction is carried out in the presence of an active methylene compound, a condensation follows immediately, giving a dithiolylidene derivative. For instance, 5-phenyl-l,2-dithiol-3-one reacts with phosphorus oxychloride and benzoylacetonitrile, giving benzoyl-(5-phenyl-l,2-dithiol-3-ylidene)-acetonitrile (Eq. 10).29... 

Dithiolium ions, l,2-dithiole-3-thiones, and 1,6,6astructural relationships which can be further extended. Compounds of this series are of peculiar interest because of the structural problems involved concerning the nature of the chemical bond and the aromaticity of the ring systems. 

Nitration of phenyl derivatives of 1,2-dithiolium ions 7.50 and 7.51 occurs at positions by arrows where (61JA2934), showing that in the dithiolium ring the positive charge is greater at the 3-(5)-position than at the 4-position. 

The 1,2- and 1,3-dithiolium ions (1 and 2) are unsaturated five-membered ring cations in which each of the two ring sulfur atoms can contribute a free pair of Zpn electrons to the mesomeric bond system. Thus both systems possess a potential aromatic sextet, and are therefore iso-7r-electronic with the tropylium ion (3), from which they... 

Until a few years ago, however, the cations 1 and 2 had aroused little interest. In 1947 Liittringhaus and Bottcher2 recognized the products of the reaction of l,2-dithiole-3-thiones ( trithiones ) with alkyl esters of inorganic acids as 3-alkylmercapto derivatives of the 1,2-dithiolium system these authors explained certain apparently unusual physical and chemical properties of these salts by resonance stabilization of the 1,2-dithiolium system.8 Thus these trithionium salts were the first derivatives of the 1,2-dithiolium ion to be identified with certainty. 

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