PUB - Publikationen an der Universität Bielefeld

Gas-phase He-I photoelectron spectra of N-tert-butyl-1,2-dihydro[1,3,2]diazaborolo[1,5-a]pyridine (3) and its thermolysis product, the parent compound 1, have been recorded and assessed by density functional theory calculations. Similarly, N-tert-butylisoindole (4) and the parent isoindole (2) were also studied. The first ionization energies of these compounds increase in the series 3 (6.75 eV)< 1 (6.85 eV)< 4 (6.9 eV)< 2 (7.3 eV). Interestingly, the HOMOs of 1 and 3 are destabilized with respect to the first ionization energy of the isomeric 1,3,2-benzodiazaboroles (ca. 7.3 eV). The dipole moment of the ground state of isoindole derivative 4 (3.48 D) is significantly greater than that of 1,2-dihydro[1,3,2]diazaborolo[1,5-a]pyridine (3; 0.996 D). Upon electronic excitation, the dipole moments increased to 5.945 and 4.735 D for 4 and 3, respectively.