Counterion-Induced Inversion of Conformer Stability of a Helquat Dication (pages 624–635)
Lukáš Severa, Michael Jirásek, Pavel Švec, Dr. Filip Teplý, Dr. Ágnes Révész, Dr. Detlef Schröder, Dr. Dušan Koval, Dr. Václav Kašička, Dr. Ivana Císařová and Dr. David Šaman
Article first published online: 19 APR 2012 | DOI: 10.1002/cplu.201200009
Subtle counterion effects in the gas phase determine the relative stabilities of different conformers of a helquat dication HQ2+ in their singly charged binary ion pairs [HQ2+⋅X−] with various counterions X−. With several counterions, the saddle conformers [SQ2+⋅X−] are more stable than the helical ones. By contrast to the variable situation in the ion pairs, in the free gaseous dications as well as in the condensed-phase salts the helical forms HQ2+ and [HQ2+⋅2X−] are strongly energetically preferred over the saddle forms.