Distonic dimer radical cation of 2,3-dihydrofuran: Quantum chemical calculations and low-temperature EPR results

The distonic dimer radical cation of the 2,3-dihydrofuran was radiolytically generated in Freon matrix and studied by low-temperature EPR spectroscopy. The structure of the dimer radical cation was also investigated using different quantum chemical methods. The BH and HLYP, similarly as ab initio HF and MP2 methods, predict in agreement with the experiment a distonic dimer radical cation, with strongly separated spin and charge. The widely used DFT B3LYP and B3PW91 methods fail in this case and lead to a wrong (delocalized) structure