A new type of C⁺⋯H^δ-(C=) bond in adducts of vinyl carbocations with alkenes.

ABSTRACT: By X-ray diffraction analysis and IR spectroscopy, it was established here that vinyl carbocations C₃H₅⁺/C₄H₇⁺ with carborane counterion CHB₁₁Cl₁₁^- form stable monosolvates C₃H₅⁺⋅C₃H₆/C₄H₇⁺⋅C₄H₈ with molecules of alkenes C₃H₆/C₄H₈. They contain molecular group =C⁺⋯H^δ--C^δ+= with a new type of bond formed by the H atom of the H-C= group of the alkene with the C atom of the C⁺=C group of the carbocation. The short C⁺----C^δ+ distance, equal to 2.44 Å, is typical of that of X----X in proton disolvates (L₂H⁺) with an quasi-symmetrical X-H⁺⋯X moiety (where X = O or N) of basic molecule L. The nature of the discovered bond differs from that of the classic H-bond by an distribution of electron density: the electron-excessive H^δ- atom from the (=)C-H group of the alkene is attached to the C⁺ atom of the carbocation, on which the positive charge is predominantly concentrated. Therefore, it can be called an inverse hydrogen bond.

SUBMITTER: Stoyanov ES 

PROVIDER: S-EPMC11006867 | biostudies-literature | 2024 Apr

REPOSITORIES: biostudies-literature