Abstract
The formation of adducts in the system containing Rh 2(OAC) 4, cyclic amidophosphite [El 2 NPO(CH 2) 3O ] and bicyclic phosphite [P(OCH 2) 3CEt] have been studied using low temperature 31P NMR. Varying the concentration of Rh 2(OAc) 4 made the signals due to a mono-adduct, a homoligated bis-adduct and a mixed bis-adduct observable in the 31P spectra. Iterational optimisation of the parameters of the spectra of symmetric bis-adducts showed a very strong correlation between the values of the coupling constants 1 J RhRh and 3 J PP. The spectrum of the asymmetric adduct (amidophosphite-Rh-Rh-phosphite) yielded a well defined estimate of 3 J PP. This value (793 Hz) is found to be between the values of the coupling constants for phosphite-phosphite and phosphite-phosphine interactions found by Boyar and Robinson. The integrals of the lines in the 31P spectra of the samples derived from different starting concentrations of Rh 2(OAc) 4 yielded values for the stability constants of the detected adducts. The mono-adduct of amidophosphite was found to be significantly more stable than that of phosphite.
Published Version
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