Quantitative reactivity model for the hydration of carbon dioxide by biomimetic zinc complexes.
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.
Bräuer
Michael
M
Continental AG, Jedekamp 30, 30419 Hannover, Germany.
Pérez-Lustres
J Luis
JL
Weston
Jennie
J
Anders
Ernst
E
D001639:Bicarbonates / Q000737:chemistry; D002245:Carbon Dioxide; D002256:Carbonic Anhydrases; D002384:Catalysis; D006860:Hydrogen Bonding; D008024:Ligands; D008958:Models, Molecular; D008968:Molecular Conformation; D015394:Molecular Structure; D013329:Structure-Activity Relationship; D013379:Substrate Specificity; D014867:Water / Q000737:chemistry; D015032:Zinc / Q000737:chemistry*
D001639:Bicarbonates; D008024:Ligands; D014867:Water; D002245:Carbon Dioxide; D002256:Carbonic Anhydrases; D015032:Zinc