Bis-iminophosphoranes containing various types of linkers between two R₃P=N moieties were electrochemically oxidized at controlled potential in situ in the electron spin resonance (ESR) cavity. For linkers constituted of phenylenes, conjugated phenylenes or merely a dicyanoethylenic bond, this oxidation led to well-resolved ESR spectra which were characterized by their g values and by their ¹H, ¹⁴N and ³¹P isotropic hyperfine constants. These coupling constants agree with those calculated by DFT for the corresponding cation radicals. Experimental and theoretical results clearly indicate that in these species the unpaired electron is mostly delocalized on the bridge and on the nitrogen atoms while the spin density on the phosphorus atoms is particularly small. Cyclic voltammetry and ESR spectra show that the nature of the bridge between the two iminophosphoranes considerably influences the oxidation potential of the compound as well as the stability of the radical cation. Information about the conformation of the precursor containing two Ph₃P=N moieties separated by a —C(CN)=C(CN)—group was obtained from its crystal structure.

Electrochemical oxidation of (C₆H₅)₃P=N(C₆H₅) and (C₆H₅)₃P=N(C₆H₅) leads to EPR spectra which reveal the dimeric structure of the resulting radical cation. In contrast to this behaviour, oxidation of bis-iminophosphorane leads to [(C₆H₅)₃P=N(C₆H₄)N=P(C₆H₅)₃]^•+: In these species the unpaired electron is delocalized on the N(C₆H₄)N moiety and the persistency of the radical depends upon the relative position of the two P=N bonds.