Substituent Effects in I-Centered Radical Cations

The inductive, resonance, and polarization effects of substituents on the ionization potential of iodine n orbitals in IX, ISnR₃, and ICCX molecules, and also on the energy of the charge-transfer band in the UV spectra of the complexes of IX and ISnR₃ with tetracyanoethylene and iodine were studied. The radical cations generated by photoionization of individual molecules in the gas phase and occurring as components of contact radical ion pairs (excited state of charge-transfer complexes) in solution have similar electronic structure. The resonance parameters ⁺ _R of organosilicon, organogermanium, and organotin substituents bound to the radical cation centers I^{+ ·} and I^{+ ·}CC were calculated for the first time.