Isolable cyclic (alkyl)(amino)carbene-phosphonyl radical adducts.

Phosphonyl radicals ([RP[double bond, length as m-dash]O]˙) and their adducts are proposed as intermediates in a number of important chemical and biological processes. Despite the great interest in these species, there are no examples of stable, isolated phosphonyl radicals or their adducts reported in the literature. Here we report the synthesis, EPR and theoretical study of stable, isolable cyclic (alkyl)(amino)carbene (cAAC)-phosphonyl radical adducts, [cAAC-P(O)R]˙ (R = OPr, Ph).