Crystallographic Snapshot of an Arrested Intermediate in the Biomimetic Activation of CO 2

The design of molecular catalysts that mimic the behavior of enzymes is a topical field of activity in emerging technologies, and can lead to an improved understanding of biological systems. Herein, we report how the bulky arms of the cations in [( n C 4 H 9 ) 4 N] + [HCO 3 ] ‐ give rise to a host scaffold that emulates the substrate binding sites in carbonic anhydrase enzymes, affording a unique glimpse of an arrested intermediate in the base‐mediated binding and activation of CO 2 .