1,3,2-Benzodiazaboroles with 1,3-Pentafluorophenyl and Tetrafluoropyridyl Substituents as Building Blocks in Luminescent Compounds

Weber L, Halama J, Böhling L, et al. 1,3,2-Benzodiazaboroles with 1,3-Pentafluorophenyl and Tetrafluoropyridyl Substituents as Building Blocks in Luminescent Compounds. European Journal of Inorganic Chemistry. 2013;2013(24):4268-4279.The reaction of N-4-trimethylsilylphenyl-3,6-di-tert-butylcarbazole (3) or N-5-trimethylsilylthien-2-yl-3,6-di-tert-butylcarbazole (4) with boron tribromide and subsequently with triphenylphosphane afforded the dibromoborylphenylcarbazole-phosphane adduct 5 or its thiophene derivative 6 as colorless solids. These adducts were converted into the new benzodiazaborole derivatives 7 and 8 by treatment with N,N-bis(pentafluorophenyl)-o-phenylenediamine (1) and 2,2,6,6-tetramethylpiperidine in hot toluene (52 or 45% yield). The analogous compounds 9 and 10 were obtained by condensing precursors 5 and 6 with bis(N,N-2,3,5,6-tetrafluoropyrid-4-yl)-o-phenylenediamine (2) in the presence of the piperidine derivative in 35 and 16% yield. Compounds 7-10 were characterized by NMR spectroscopy (H-1, B-11, C-13, F-19) and mass spectrometry. The molecular structure of 8 was elucidated by X-ray diffraction analysis. The borylated systems show intense blue luminescence upon UV irradiation