Abstract: The electronic structure of 14 O-ethyl-O-aryl phosphoramidothioates was studied by using a quantum chemical method of CNDO/2. The nucleophilic superdelocalizability on phosphorus and bond order of P-Oare found to show some linear relationship with experimental reactivity. Form the results, the pharmacology is suggeeested. The relationship of the pharmacodynamic conformation with the stable conformation is also discussed.

Key words: Phosphoramidothioate, Superdelocalizability, Pharmacology