EPR studies of 1-methyl-2-substituted-5-pyrrolylcarbonyl fluorinated nitroxides and dual-parameter correlation analysis of their hyperfine splitting constants

Three series of new 1-methyl-2-substituted-5-pyrrolylcarbonyl fluorinated nitroxides, i.e., 3 (R f =C 2 F 5 ), 4 (R f = n -C 3 F 7 ) and 5 (R f = n -C 7 F 15 ), generated by the H-abstraction/spin-trapping reaction of eleven 1 -methyl-2-substituted-pyrrole-5-carbaldehydes ( 6 ) with the H-abstracting agent [R f N(O • )R f ] 1 and the spin-trapping agent R f NO 2 , were studied by EPR. Correlation analysis of their a N values with polar and spin-delocalization substituent constants shows that a N values are mainly affected by the polar effect of the 2-substituent, but the spin-delocalization effect also exists.