title: UV-photoelectron spectroscopy of 1,2- and 1,3-azaborines: a combined experimental and computational electronic structure analysis.
abstract: We present a comprehensive electronic structure analysis of structurally simple BN heterocycles using a combined UV-photoelectron spectroscopy (UV-PES)/computational chemistry approach. Gas-phase He I photoelectron spectra of 1,2-dihydro-1,2-azaborine 1, N-Me-1,2-BN-toluene 2, and N-Me-1,3-BN-toluene 3 have been recorded, assessed by density functional theory calculations, and compared with their corresponding carbonaceous analogues benzene and toluene. The first ionization energies of these BN heterocycles are in the order N-Me-1,3-BN-toluene 3 (8.0 eV) < N-Me-1,2-BN-toluene 2 (8.45 eV) < 1,2-dihydro-1,2-azaborine 1 (8.6 eV) < toluene (8.83 eV) < benzene (9.25 eV). The computationally determined molecular dipole moments are in the order 3 (4.577 D) > 2 (2.209 D) > 1 (2.154 D) > toluene (0.349 D) > benzene (0 D) and are consistent with experimental observations. The λ(max) in the UV-vis absorption spectra are in the order 3 (297 nm) > 2 (278 nm) > 1 (269 nm) > toluene (262 nm) > benzene (255 nm). We also establish that the measured anodic peak potentials and electrophilic aromatic substitution (EAS) reactivity of BN heterocycles 1-3 are consistent with the electronic structure description determined by the combined UV-PES/computational chemistry approach.
authors.affiliation: Institut des Sciences Analytiques et de Physico-Chimie pour l'Environnement et les Matériaux, UMR CNRS 5254, Université de Pau et des Pays de l'Adour, Avenue de l'Université, BP 1155, 64 013 Pau Cedex, France. anna.chrostowska@univ-pau.fr
authors.forename: Anna
authors.initials: A
authors.lastname: Chrostowska
authors.forename: Senmiao
authors.initials: S
authors.lastname: Xu
authors.forename: Ashley N
authors.initials: AN
authors.lastname: Lamm
authors.forename: Audrey
authors.initials: A
authors.lastname: Mazière
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Weber
authors.forename: Alain
authors.initials: A
authors.lastname: Dargelos
authors.forename: Patrick
authors.initials: P
authors.lastname: Baylère
authors.forename: Alain
authors.initials: A
authors.lastname: Graciaa
authors.forename: Shih-Yuan
authors.initials: SY
authors.lastname: Liu
mesh_terms: D001896:Boron Compounds / Q000737:chemistry*; D055664:Electrochemical Techniques; D004583:Electrons; D008958:Models, Molecular; D056951:Photoelectron Spectroscopy; D014466:Ultraviolet Rays
chemical_list: C556261:1,2-azaborine; D001896:Boron Compounds