TITLE:
Pseudo Jahn-Teller Effect in Puckering and Planarization of Heterocyclic Compounds
AUTHORS:
Natalia Gorinchoy
KEYWORDS:
Pseudo Jahn-Teller Effect (PJTE), Vibronic Coupling, Puckering and Planarization in Heterocyclic Systems
JOURNAL NAME:
International Journal of Organic Chemistry,
Vol.8 No.1,
March
12,
2018
ABSTRACT: The goal of this brief partly review paper is to summarize the results of
the works published over the last few years
regarding the origin of the out-of-plane distortions (puckering) of
heterocyclic compounds. In all the papers devoted to this problem, it is shown that the
instability of planar configurations of heterocyclic molecules leading to
symmetry breaking and distortions is induced by the pseudo Jahn-Teller effect
(PJTE). Special attention in this work is paid to the mechanism of suppression
and enhancement of the PJTE distortions of heterocycles by oxidation,
reduction, and chemical substitutions. It is demonstrated that oxidation of
1,4-dithiine containing compounds leads to suppression of
the PJTE and to restoration of their planar nuclear configurations. An example
of a dibenzo[1,2]dithiine molecule is used to demonstrate the mechanism of enhancement
of the PJTE by reduction. It is shown that the reduction of the neutral C12H8S2 molecule up to the dianion (C12H8S2)2- enhances the PJTE, followed by the S-S bond cleavage and significant structural
distortions of the system. The change of the PJTE by chemical substitutions,
accompanied either by puckering or by planarization of heterocyclic compounds,
is discussed using as examples 1,4-ditinine and its S-oxygenated derivatives.