Abstract Iminoxy radicals of a new type, having the general formula RC ([DOUBLE BOND] NO) P (O)(OEt) 2, were synthesized and characterized by means of ESR spectroscopy. The presence of two isomers due to the different position of the C [DOUBLE BOND] NO fragment with respect to the R substituent and the P atom, and the relative stability of the isomers, was established. The influence of the R substituent on the relative population of the isomers ...