2,6-Diazaanthracene-9,10-dione and its Radical Anion-A Structural and Spectroscopic Investigation

摘要

An analysis of the structure,vibrational and electronic spectra,and the molecular orbitals of 2,6-diazaanthracene-9,10-dione (DAAD) (1) and its radical anion is presented.Strong pi-stacking is seen in the crystal structure of (1) and observed bond lengths and angles are in good agreement with those calculated with the B3LYP/6-31(d) method.The vibrational spectra of (1) show strong bands at 1686 cm~(-1) (IR) and 1676cm~(-1) (Raman) corresponding to the antisymmetric and symmetric C=O stretch,respectively,in good agreement with calculated data.Electrochemical or chemical reduction to (1)~(.-) results in a new spectrum with a strong with a strong absorption due to the antisymmetric stretch at 1481 cm~(-1) (predicted 1470cm~(-1)).The lowest energy electronic transition for (1) occurs at 317nm;new transitions at lower energy (403,573,and 910nm)are seen in the spectrum of (1)~(.-).The dark purple radical anion (1)~(.-) was isolated as the Cp_2Co~+ salt but its ESR spectrum did not display hyperfine coupling.