Studies of Equilibria and Shift Reagents

Studies of Equilibria and Shift Reagents.—N.m.r. studies of the exchange of halogen in boron trihalide adducts of trimethylphosphine, its oxide, and sulphide,49 and exchange of chloro- and methoxy-groups between methylphosphino and methyl-silyl or -germyl moieties,80 have been reported. The rates of ionization of phosphoranes 

Shift reagents have been used for the configurational and conformational analysis of cyclic phosphites (34).65 The reagent Eu(fod)3 moved Ha of the vinylphosphine oxide (35) twice as far downfield as the corresponding proton in the spectrum of the 

Z-isomer.56 The isomers of the cyclic phosphonate (36) were assigned from the effect of Eu(dpm)3 on the methyl signal.67 Shifts of the butyl signals of tributyl phosphate by europium chloride have also been recorded.58 

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