Experimental and theoretical study of the electronic absorption spectra of some 1,2-benzoquinone diazides: Closed-open tautomerism

摘要

The electronic absorption spectra as well as molecular orbital (MO) calculations at the ab initio level of some 1,2-benzoquinone diazides have been studied. The results of spectral study support the open isomer over the closed one (1,2,3-oxadiazole derivative) and indicate the contribution of both the benzenoid and quinonoid structures to the molecule. Spectral results were confirmed by MO calculations. The results of the latter gave a lower total energy for a benzoquinone diazide than for 1,2,3-benzoxadiazole structure. Bond length and charge density indicate the contribution of both quinonoid and benzenoid structures for the studied compounds. (C) 2000 John Wiley & Sons, Inc. [References: 21]