Quantitative Reactivity Model for the Hydration of Carbon Dioxide by Biomimetic Zinc Complexes

• Published in: Inorganic chemistry Vol. 41; no. 6; pp. 1454 - 1463
• Main Authors: Bräuer, Michael, Pérez-Lustres, J. Luis, Weston, Jennie, Anders, Ernst
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 25-03-2002
• Subjects: Bicarbonates - chemistry; Carbon Dioxide; Carbonic Anhydrases; Catalysis; Hydrogen Bonding; Ligands; Models, Molecular; Molecular Conformation; Molecular Structure; Structure-Activity Relationship; Substrate Specificity; Water - chemistry; Zinc - chemistry
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/ic0010510

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.