Crystal and Molecular Structures of Organophosphorus Insecticides. 13. S-Isopropyl 0-Methyl 0-(3,5,6-Trichloro-2-pyridyl) Phosphoramidothioate and Dimethoate

Authors

Rick L. Lapp, Iowa State University
Robert A. Jacobson, Iowa State University

Date of this Version

1980

Comments

Published in J. Agric. Food Chem., Vol. 28, No. 4, 1980.

Abstract

The crystal and molecular structures of S-isopropyl O-methyl O-(3,5,6-trichloro-2-pyridyl) phosphoramidothioate, C₉H₁₂N₂O₂PSC1₃, and dimethoate [ O,O-dimethyl S-(N-methylcarbamoyl)methyl phosphorodithioate], C₅H_I2NO₃PS₂, have been determined by three-dimensional X-ray analysis. The former compound crystallizes in the triclinic space group P1 with a = 10.319 (5) Å, b = 10.730 (6) Å, c = 8.44 (4) Å, a = 99.01 (2)°, β = 114.02 (l)°, and y = 62.64 (1)° with Z = 2, and the latter compound crystallizes in the monoclinic space group P2₁ with a = 6.574 (2) Å, b = 9.354 (2) Å, c = 9.885 (2) Å, and β = 107.4 (2)° with two molecules per unit cell. The structures were refined by a full-matrix, least-squares procedure to final residual indices of R = 0.058 and 0.068, respectively, using reflections with F_° > 3σ(F_°). Atomic charge densities were calculated via CNDO/2 methods in order that positive charge center separations as well as geometric factors could be compared between these insecticides, acetylcholinesterase, and previous insecticides studied in this series.