ADDITIVITY RULE OF P-31 CHEMICAL-SHIFTS F OR THIOPHOSPHATES

P-31 NMR spectra of about 80 thiophosphates synthesized in our laborat ory were determined. An empirical additivity equation, a set of chemic al shift parameters and stereoelectronic effect parameters, which were proposed by the authors, can be used for calculating P-31 chemical sh ifts of phosphates and thiophosphates more accurately. The mean error and the standard deviation between calculated and observed values of P -31 chemical shifts are +/-0.096 and +/-0.13 respectively. Structures of thiophosphates can be predicted by using the additivity equation. T he dependence of the P-31 chemical shifts upon electronegativity, bond -angle and stereoelectronic effect was discussed theoretically.