ELECTRONIC-SPECTRA AND STRUCTURE OF 2-BROMOPICOLINES, THEIR N-OXIDES AND 2-BROMO-4-NITROPICOLINE N-OXIDES

UV spectra of 2-bromopicolines, their N-oxides and 2-bromo-4-nitropico line N-oxides are presented and the influence of substituents on lambd a(max) and epsilon(max) of spectral bands are discussed. The electroni c spectra were calculated using modified INDO method. Transition energ ies, intensities and assignments were compared with UV spectra. The de gree of intramolecular CT in 2-bromopicoline N-oxides is greater than those in 2-bromopicolines and smaller than those in 2-bromo-4-nitropic oline N-oxides. Differences of HOMO-LUMO energies point out that the s usceptibilities in photochemical reaction lies in the order: 2-bromo-4 -nitroplcoline N-oxides > 2-bromopicoline > N-oxides 2-bromopicolines.