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The 'H and "P N M R spectra of 3-amino-3-phosphonatopropionic acid, a phosphonic derivative of aspartic acid, have been measured and completely analysed for 14 pH values. me vicinal coupling co~tants, ' J m and 'J(HP), were used to obtain information on the rotational isomerism of the amino acid. The most stable conformer is the one where the phosphonic and P-carboxyl groups are in trans position to each other.

By the use of the 'H-lH and 'H-"P coupling constants in two analogues of aspartic acid i.e. 3-amino-3-phosphonatopropionic and 3-amino-3-(methylphosphinato) propionic acids, it was shown that the six parameter formulation for the evaluation of mole fractions of three staggered ethanic rotamers is not necessarily better than the two parameter formulation in this system. The results allowed the recommendation of the following values for the two vicinal proton parameters i.e. J(HH)g=2.3, J(HH) t = 13.9 and for the two vicinal proton-phosphorus parameters i.e. J(HP)g= 4.2, J(HP)t= 33.0 Hz.

lminoxy radicals containing the diethyl phosphonate group have been synthesized and characterized by means of EPR spectroscopy. Structures of the Z and E isomers have been established on the basis of hyperfine splitting due t o 14N, 31P, and 'H nuclei. The higher stability of the E isomer over the Z isomer has been established by analysis of anisotropic spectra. The source of a dependence of the

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