Substitution of H Atoms in Unsaturated (Vinyl-Type) Carbocations by Cl or O Atoms

• Published in: International journal of molecular sciences 2023-06, Vol.24 (13), p.10734
• Main Authors: Stoyanov, Evgenii S, Bagryanskaya, Irina Yu, Stoyanova, Irina V
• Format: Article
• Language: English
• Subjects: Acetylene; Carbon; carborane salts; Cations; Cations - chemistry; Chlorine; Chlorine - chemistry; Crystals; Infrared spectroscopy; Ions; IR spectroscopy; Olefins; Spectrum analysis; vinyl carbocations; X-ray diffraction
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms241310734

Introduction of Cl and O atoms into C -vinyl carbocations was studied by X-ray diffraction analysis and IR spectroscopy. Chlorine atoms are weak electron acceptors in ordinary molecules but, within vinyl carbocations, manifest themselves as strong electron donors that accept a positive charge. The attachment of a Cl atom directly to a C=C bond leads to an increase in the e-density on it, exceeding that of the common double bond. The positive charge should be concentrated on the Cl atom, and weak δ may appear on the C=C bond. More distant attachment of the Cl atom, e.g., to a C atom adjacent to the C=C bond, has a weaker effect on it. If two Cl atoms are attached to the C atom of the vinyl cation, as in Cl C C HC HCH , then the cation switches to the allyl type with two practically equivalent and almost uncharged C C C bonds. When such a strong nucleophile as the O atom is introduced into the carbocation, a protonated ester molecule with a C-O(H )-C group and a C=C bond forms. Nonetheless, in the future, there is still a possibility of obtaining carbocations with a non-protonated C-O-C group.