Phosphorus-Containing Cyclohexanes. Nuclear Magnetic Resonance Studies and Conformational Analysis of 1,3,2-Dithiaphosphorinanes

Proton, carbon-13, and phosphorus-31 NMR spectroscopic data were obtained for a variety of tricoordinate 1,3,2-dithiaphosphorinanes as well as tetracoordinate 2-oxo and 2-thiono derivatives. The tricoordinate compounds adopt a chair conformation in which an axial orientation is strongly preferred for many polar and nonpolar P substituents (CH3, C2H2, C6H6, OCH3, Cl), but an equatorial orientation is strongly preferrd for the P-tert-butyl group. The 2-oxo compounds show a tendency to populate a twist conformation in solution, but the 2-thiono compounds do not. Single-crystal X-ray analyses of 11 derivatives (5,6,7a, 11b, 19, 20a, 22,23,24,28,31) are employed to verify structural assignments and to provide solid-state conformational viewpoints. Three 2-oxo compounds (5, 6, and 28) adopt a twist conformation in the solid state. A chloride- catalyzed chlorine-exchange process in 2-chloro-1,3,2-dithiaphosphorinanes and the stereospecificity of certain 1H and 13C NMR parameters are discussed. A general discussion of twist preferences in 1,3,2-dithiaphosphorinanes, and congeneric systems, is presented. © 1981, American Chemical Society. All rights reserved.

Duke Scholars

Author Andrew T. McPhail Chemistry