Structures and Fragmentations of Protonated Benzene and Its Derivatives. I.

Abstract

Using STO-3G geometry optimization was carried out on the benzenium ion and p- and F-protonated fluorobenzenes. Electronic structures, geometries, and heats of formation of protonated phenol, toluene, aniline, benzaldehyde, benzonitrile, fluorobenzene, and chlorobenzene were obtained by MINDO/3 and compared in an attempt to explain absense of C₆H₅⁺ ion in chemical ionization mass spectra of benzaldehyde and benzonitrile. The unstability of N-protonated aniline has been interpreted in terms of breakage of the conjugation between lone pair electrons and π-electrons.