Recent developments in the chemistry of 1,3,2-diazaborolines-(2,3-dihydro-1H-1,3,2-diazaboroles)

1,3,2-Diazaborolines (2,3-dihydro-1H-1,3,2-diazaboroles) are compounds at the interface between inorganic, organometallic and organic chemistry. The planar rings with 6π-electrons may be regarded as heteroarenes, as evident by NMR and photoelectron spectra and confirmed by quantum chemical studies. High-yield syntheses of functionalized 1,3,2-diazaborolines have been elaborated, providing a prolific area of chemistry. Conjugation of the vacant 2pz-orbital on the boron center with the π* orbital of attached organic π-systems proved to be responsible for unique absorption and emission characteristics of 1,3,2-diazaborolinyl functionalized biphenyls, thiophenes and dithiophenes. Most of the functionalized diazaborolines show clean irreversible oxidation waves in their cyclovoltammograms.