Nuclear magnetic resonance and stereochemistry of organophosphorus compounds: dithia-phospholanes and dithia-phosphorinanes

The full N.M.R. spectrum analysis of two different kinds of heterocycles containing phosphorus and sulfur atoms (1,3,2-dithia-phospholanes and 1,3,2-dithia-phosphorinanes) with various groups attached to the phosphorus is reported in the present study. The results show that the 3J(P,H) N.M.R. coupling are quite independent upon the nature of the R group attached to the phosphorus. A change of sign have been observed in the 3J(P,H) values. The absolute value of the 3J(P,H) coupling is small, on the opposite of the 4J(P,H) which may be as high as 7 Hz. The hetero-cycle conformation is discussed by examining the 3J(H,H) values and using Karplus-like relationship which is established for a S-CH2-CH2-S fragment. A carbon edge envelope conformation with a 40 deg. torsion angle around the C-C bond is proposed for the fine membered ring. A slightly distorted chair conformation is proposed for the six membered ring. (author)