Copper Complexes of Quinoxaline N-Oxide Derivatives

Abstract

Synthesis and spectral properties of copper(ll)halide complexes withquinoxaline N-exides, N, N -dioxides and their derivatives have been investigated. Most of the obtained complexes were 2:1 complexes, while quinoxaline 1, 4-diexide and 2-methyl-3-phenylquinoxa1ine 1, 4- dioxide formed 1:1 complexes, Far infrared spectral analyses indicated that Cu-Cl stretching frequencies appear at 270v350 cm i, and Cu-Br frequencies at 226"v264 cm-w i. For the copper(E) halide-quinoxaline N, N -dioxides complexes the Cu-O stretching frequencies were observedin the range 329rv419 cm-i; however, omplexes of quinoxaline N-oxides (except that of 3-phenylquinoxaline 1-oxide) did not show any Cu-O frequencies.
The diffuse reflectance spectra of copper halide-quinoxaline N, N -dioxides complexes showed 3 bands in the region of 450.v900 nm. The d-d transition bands of these complexes appear at much longer wavelengthes (790.v900 nm) than those of the quinoxaline N-oxides complexes.
Furthermore, the in, frared spectra of quinexaline N-oxides and N, N -dioxides, and 14 kinds of their 2- and 2, 3-substitUted derivatives were measured. Their characteristic N-O stretching frequencies were observed in the region of 1280N1380 cmewi, and they were scarcely shifted by the hydrogen bond formation caused by addition of MeOH to their solutions in non-polar solvents.