Chemical behaviour of hydrocarbon salts in solution

The brown colour of a chloroform solution of the salt [24 2 ] suggests the formation of the covalent hydrocarbon [24-2] by cation-anion combination (33). The structure of [24-2] was determined by and nmr spectroscopy in CDCI3 (Okamoto et al., 1988, 1990). 

Recently two additional examples, [26-2] and [28-2], of hydrocarbons existing solely in solution have been found in the chloroform solutions of hydrocarbon salts [26 2 ] and [28 2 ] (Table 5) (Komatsu et al., 1989 Takeuchi et al., 1993). 

A SOLUTION IN WHICH IONIC, RADICAL AND COVALENT SPECIES COEXIST IN EQUILIBRIA 

If the cation moiety of the dissociative hydrocarbon has marked electron-accepting properties and the anion moiety is readily oxidized, a similar equilibrium is expected. An example has been found with hydrocarbon [28-2] (Komatsu et al., 1989 Okamoto et al., 1990). 

The hydrocarbon salt [28 2 ] dissolves in DMSO without any reaction, giving a deep green solution. In contrast, when this salt is dissolved in chloroform, it affords an orange-brown solution, spectrophotometrically suggesting the formation of a hydrocarbon [28-2]. The formation of the covalent hydrocarbon in chloroform is also supported by the fact that the anion [2 ] is regenerated upon dilution of the freshly prepared solution with 10 volumes of DMSO. 

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