Web Release Date: January 24,
The Structure and Stability of Biological Metaphosphate, Phosphate, and Phosphorane Compounds in the Gas Phase and in Solution
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Contribution from the Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455-0431, and Kimika Fakultatea, Euskal Herriko Unibertsitatea, P.K. 1072, 20080 Donostia, Euskadi, Spain
Received April 14, 2003
Abstract:
Density functional calculations of a series of metaphosphates, acyclic and cyclic phosphates and phosphoranes relevant to RNA catalysis are presented. Solvent effects calculated with three well-established solvation models are analyzed and compared. The structure and stability of the compounds are characterized in terms of thermodynamic quantities for isomerization and ligand substitution reactions, gas-phase proton affinities, and microscopic solution pKa values. The large dataset of compounds allows the estimation of bond energies to determine the relative strengths of axial and equatorial P-O phosphorane single bonds and P-O single and double bonds in metaphosphates and phosphates. The relative apicophilicty of hydroxyl and methoxy ligands in phosphoranes are characterized. The results presented here provide quantitative insight into RNA catalysis and serve as a first step toward the construction of a high-level quantum database for development of new semiempirical Hamiltonian models for biological reactions
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