ESR and Optical Studies on the EDA Complexes of Di-t-butyl-N-oxide Radical

It has been confirmed that di-t-butyl-N-oxide (DTBNO) forms EDA complexes with various electron acceptors, and the resulting complexes show CT (charge transfer) absorption bands. Wave-numbers of the CT bands agreed satisfactorily with theory. Charge distributions in the EDA complexes of DTBNO, including hydrogen bonded complexes with proton donors, have been investigated by means of ESR. From the effect of the EDA complex formation upon the hyperfine coupling constant of 14N of DTBNO, contribution of electrostatic forces to complex formation has been demonstrated. However, in the case of complexes with strong acceptors such as tetracyanoethylene, the values of the hyperfine coupling constant have indicated a significant contribution of CT interaction to complex formation.