CF3: An Electron‐Withdrawing Substituent for Aromatic Anion Acceptors? "Side‐On" versus "On‐Top" Binding of Halides. Issue 20 (8th April 2016) - Albrecht, Markus
Abstract: The ability of multiple CF3 ‐substituted arenes to act as acceptors for anions is investigated. The results of quantum‐chemical calculations show that a high degree of trifluoromethyl substitution at the aromatic ring results in a positive quadrupole moment. However, depending on the polarizability of the anion and on the substitution at the arene, three different modes of interaction, namely Meisenheimer complex, side‐on hydrogen bonding, or anion–π interaction, can occur. Experimentally, the side‐on as well as a η 2 ‐type π‐complex are observed in the crystal, whereas in solution only side‐on binding is found. Abstract : The place to be ! A subtle interplay of electronic effects at the aromatic system and at aromatic H atoms in connection with the polarizability of the anion controls the position of anions with respect to CF3 ‐substituted aromatics.