UV-Photoelectron Spectroscopy of 1,2- and 1,3-Azaborines: A Combined Experimental and Computational Electronic Structure Analysis

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• 作者：Anna Chrostowska ; Senmiao Xu ; Ashley N. Lamm ; Audrey Mazi猫re ; Christopher D. Weber ; Alain Dargelos ; Patrick Bayl猫re ; Alain Graciaa ; Shih-Yuan Liu
• 刊名：The Journal of the American Chemical Society
• 出版年：2012
• 出版时间：June 20, 2012
• 年：2012
• 卷：134
• 期：24
• 页码：10279-10285
• 全文大小：451K
• 年卷期：v.134,no.24(June 20, 2012)
• ISSN：1520-5126

文摘

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 位_max in the UV鈥搗is 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鈥?b>3 are consistent with the electronic structure description determined by the combined UV-PES/computational chemistry approach.