N-ヘテロ芳香族の電子的性状(第14報) : 4-Nitropyridine 1-Oxideとアニリン誘導体との電荷移動型相互作用

抄録

Spectrophotometric studies were made on the interactions between 4-nitropyridine 1-oxide (4-NPO) and aniline derivatives, and participation of n-π^* type charge-transfer in the complex formation, wherein amino moiety of aniline acts as the electron donor and 4-NPO as electron acceptor, was deduced from the following results. (1) New absorption bands which appeared in the visible region of the difference spectra of mixed solutions of 4-NPO and aniline derivatives were characteristic of charge-transfer complexes in that they shifted toward red with increasing polarity of the solvents. (2) From the gradient of the straight line obtained by plotting Z-values of solvents versus transition energies of 4-NPO-aniline complex in various solvents, it was clarified that the new absorption bands were assignable to n→π^* transitions. (3) The new absorption bands were susceptible to pH changes and diminished in the acid range, indicating participation of n electron of amino group of aniline in the complex formation. (4) Examination of ε, K and ΔH values of 4-NPO-aniline derivative complexes revealed that methylation of amino group of aniline had a steric hindrance effect upon complex formation.