The Correlation of Structure Features and Valent Phosphorus State with NMR Parameters of Some Five-Membered Heterocycles

NMR parameters of the phosphorus-containing molecules are known to be affected by the phosphorus coordination number. Very little has been published about the theory proper and about the correlation characteristics of this influence. In order to obtain some information about this problem we have synthesized a number of phospholene and oxaphospholene derivatives containing phosphorus in various valent states.