The Chloronium Cation [(CH)Cl] and Unsaturated C-Carbocations with C=C and C≡C Bonds in Their Solid Salts and in Solutions: An H/C NMR and Infrared Spectroscopic Study.

Solid salts of the divinyl chloronium (CH)Cl cation () and unsaturated CHCl and CH carbocations with the highly stable CHBHal anion (Hal=F, Cl) were obtained for the first time. At 120 °C, the salt of the chloronium cation decomposes, yielding a salt of the CH cation. This thermally stable (up to 200 °C) carbocation is methyl propargyl, CH≡C-C-H-CH (), which, according to quantum chemical calculations, should be energetically much less favorable than other isomers of the CH cations. Cation readily attaches HCl to the formal triple C≡C bond to form the CHCl=CH-CH-CH cation (). In infrared spectra of cations , , and , frequencies of C=C and C≡C stretches are significantly lower than those predicted by calculations (by 400-500 cm). Infrared and H/C magic-angle spinning NMR spectra of solid salts of cations and and high-resolution H/C NMR spectra of in solution in SOClF were interpreted. On the basis of the spectroscopic data, the charge and electron density distribution in the cations are discussed.