H-Bonded anion–anion complex trapped in a squaramido-based receptor†
Abstract
Herein we report the experimental observation (X-ray characterization) of an anion–anion complex (anion = hydrogen fumarate) stabilized by H-bonds that is trapped in a secondary squaramide receptor. High level ab initio calculations indicate that the anion–anion complex is thermodynamically unstable but kinetically stable with respect to the isolated anions.