M. Bräuer, J. L. Pérez-Lustres, Jennie Weston
Feb 20, 2002
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Journal
Inorganic chemistry
Abstract
A quantitative structure-reactivity relationship has been derived from the results of B3LYP/6-311+G calculations on the hydration of carbon dioxide by a series of zinc complexes designed to mimic carbonic anhydrase. The reaction mechanism found is general for all complexes investigated. The reaction exhibits a low (4-6 kcal/mol) activation energy and is exothermic by about 8 kcal/mol. The calculations suggest an equilibrium between Lipscomb and Lindskog intermediates. The effectiveness of the catalysis is a function of the nucleophilicity of the zinc-bound hydroxide and the nucleofugicity of the zinc-bound bicarbonate. Hydrogen bridging of the bicarbonate to NH moieties in the ligands also plays an important role.