Acetaldehyde hydration by zinc–hydroxo complexes: coordination number expansion during catalysis

Abstract

The complexes [Zn(tren)(OH)]⁺ and [Cd(Me₆tren)(OH)]⁺ are excellent catalysts for the hydration of acetaldehyde while the closely related complex [Zn(Me₆tren)(OH)]⁺ does not catalyze the reaction, consistent with the notion that zinc ions require the ability to accommodate expanded coordination numbers in hydrolytic reactions such as those catalyzed by the enzyme carbonic anhydrase.