Ab Initio Studies on Hexavalent Phosphorus Compounds
Abstract
The reaction of some organophosphorus compounds with cholinesterase is thought to proceed by nucleophilic substitution through a pentacoordinate trigonal bypyramidal structure. Recently, Robert Holmes suggested that a hexacoordinate species might be involved instead. Hartree-Fock calculations were performed on a series of hexavalent phos-phorus compounds in which a nitrogen atom provided both electrons for the sixth bond thereby forming an octahedral complex. In general, electron-withdrawing groups on the phosphorus atom increased the strength of the coordinate covalent bond between the nitrogen and phosphorus atoms. When the hexavalent phosphorus species was constructed by addition of ammonia and hydroxide to a phosphonate, the P-N distance was over 4 A. This weak interaction is inconsistent with the hypothesis that nitrogen ligands accelerate the rate of hydrolysis by forming a hexavalent transition.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 2002
- Accession Number
- ADA436055
Entities
People
- Ashley L. Wilson
- William E. White
Organizations
- Edgewood Chemical Biological Center