The Chloronium Cation [(C₂H₃)₂Cl⁺] and Unsaturated C₄-Carbocations with C=C and C≡C Bonds in Their Solid Salts and in Solutions: An H¹/C¹³ NMR and Infrared Spectroscopic Study.

ABSTRACT: Solid salts of the divinyl chloronium (C₂H₃)₂Cl⁺ cation (I) and unsaturated C₄H₆Cl⁺ and C₄H₇⁺ carbocations with the highly stable CHB₁₁Hal₁₁^- 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 C₄H₅⁺ cation. This thermally stable (up to 200 °C) carbocation is methyl propargyl, CH≡C-C⁺-H-CH₃ (VI), which, according to quantum chemical calculations, should be energetically much less favorable than other isomers of the C₄H₇⁺ cations. Cation VI readily attaches HCl to the formal triple C≡C bond to form the CHCl=CH-C⁺H-CH₃ cation (VII). In infrared spectra of cations I, VI, and VII, frequencies of C=C and C≡C stretches are significantly lower than those predicted by calculations (by 400-500 cm^-1). Infrared and ¹H/¹³C magic-angle spinning NMR spectra of solid salts of cations I and VI and high-resolution ¹H/¹³C NMR spectra of VII in solution in SO₂ClF were interpreted. On the basis of the spectroscopic data, the charge and electron density distribution in the cations are discussed.

SUBMITTER: Stoyanov ES 

PROVIDER: S-EPMC9409342 | biostudies-literature | 2022 Aug

REPOSITORIES: biostudies-literature